If you compared the files line by line can you find something that is different?

LT51420402011292KHCOO_MTL.txt GROUP = METADATA_FILE_INFO ORIGIN = "Image courtesy of the U.S. Geological Survey" REQUEST_ID = "0101302267960_00007" LANDSAT_SCENE_ID = "LT51420402011292KHC00" FILE_DATE = 2013-02-26T14:02:36Z STATION_ID = "KHC" PROCESSING_SOFTWARE_VERSION = "LPGS_12.1.4" DATA_CATEGORY = "NOMINAL" END_GROUP = METADATA_FILE_INFO GROUP = PRODUCT_METADATA DATA_TYPE = "L1T" DATA_TYPE_L0RP = "TMR_L0RP" ELEVATION_SOURCE = "GLS2000" OUTPUT_FORMAT = "GEOTIFF" EPHEMERIS_TYPE = "DEFINITIVE" SPACECRAFT_ID = "LANDSAT_5" SENSOR_ID = "TM" SENSOR_MODE = "BUMPER" WRS_PATH = 142 WRS_ROW = 040 DATE_ACQUIRED = 2011-10-19 SCENE_CENTER_TIME = 04:42:07.7860000Z CORNER_UL_LAT_PRODUCT = 29.77973 CORNER_UL_LON_PRODUCT = 82.79439 CORNER_UR_LAT_PRODUCT = 29.83584 CORNER_UR_LON_PRODUCT = 85.30561 CORNER_LL_LAT_PRODUCT = 27.84604 CORNER_LL_LON_PRODUCT = 82.87150 CORNER_LR_LAT_PRODUCT = 27.89786 CORNER_LR_LON_PRODUCT = 85.33677 CORNER_UL_PROJECTION_X_PRODUCT = 93300.000 CORNER_UL_PROJECTION_Y_PRODUCT = 3301800.000 CORNER_UR_PROJECTION_X_PRODUCT = 336300.000 CORNER_UR_PROJECTION_Y_PRODUCT = 3301800.000 CORNER_LL_PROJECTION_X_PRODUCT = 93300.000 CORNER_LL_PROJECTION_Y_PRODUCT = 3087000.000 CORNER_LR_PROJECTION_X_PRODUCT = 336300.000 CORNER_LR_PROJECTION_Y_PRODUCT = 3087000.000 REFLECTIVE_LINES = 7161 REFLECTIVE_SAMPLES = 8101 THERMAL_LINES = 7161 THERMAL_SAMPLES = 8101 FILE_NAME_BAND_1 = "LT51420402011292KHC00_B1.TIF" FILE_NAME_BAND_2 = "LT51420402011292KHC00_B2.TIF" FILE_NAME_BAND_3 = "LT51420402011292KHC00_B3.TIF" FILE_NAME_BAND_4 = "LT51420402011292KHC00_B4.TIF" FILE_NAME_BAND_5 = "LT51420402011292KHC00_B5.TIF" FILE_NAME_BAND_6 = "LT51420402011292KHC00_B6.TIF" FILE_NAME_BAND_7 = "LT51420402011292KHC00_B7.TIF" GROUND_CONTROL_POINT_FILE_NAME = "LT51420402011292KHC00_GCP.txt" REPORT_VERIFY_FILE_NAME = "LT51420402011292KHC00_VER.txt" BROWSE_VERIFY_FILE_NAME = "LT51420402011292KHC00_VER.jpg" METADATA_FILE_NAME = "LT51420402011292KHC00_MTL.txt" CPF_NAME = "L5CPF20111001_20111231.06" END_GROUP = PRODUCT_METADATA GROUP = IMAGE_ATTRIBUTES CLOUD_COVER = 25.00 IMAGE_QUALITY = 9 SUN_AZIMUTH = 148.42888829 SUN_ELEVATION = 46.01283362 GROUND_CONTROL_POINTS_MODEL = 126 GEOMETRIC_RMSE_MODEL = 4.690 GEOMETRIC_RMSE_MODEL_Y = 3.416 GEOMETRIC_RMSE_MODEL_X = 3.214 GROUND_CONTROL_POINTS_VERIFY = 2986 GEOMETRIC_RMSE_VERIFY = 0.318 END_GROUP = IMAGE_ATTRIBUTES GROUP = MIN_MAX_RADIANCE RADIANCE_MAXIMUM_BAND_1 = 193.000 RADIANCE_MINIMUM_BAND_1 = -1.520 RADIANCE_MAXIMUM_BAND_2 = 365.000 RADIANCE_MINIMUM_BAND_2 = -2.840 RADIANCE_MAXIMUM_BAND_3 = 264.000 RADIANCE_MINIMUM_BAND_3 = -1.170 RADIANCE_MAXIMUM_BAND_4 = 221.000 RADIANCE_MINIMUM_BAND_4 = -1.510 RADIANCE_MAXIMUM_BAND_5 = 30.200 RADIANCE_MINIMUM_BAND_5 = -0.370 RADIANCE_MAXIMUM_BAND_6 = 15.303 RADIANCE_MINIMUM_BAND_6 = 1.238 RADIANCE_MAXIMUM_BAND_7 = 16.500 RADIANCE_MINIMUM_BAND_7 = -0.150 END_GROUP = MIN_MAX_RADIANCE GROUP = MIN_MAX_PIXEL_VALUE QUANTIZE_CAL_MAX_BAND_1 = 255 QUANTIZE_CAL_MIN_BAND_1 = 1 QUANTIZE_CAL_MAX_BAND_2 = 255 QUANTIZE_CAL_MIN_BAND_2 = 1 QUANTIZE_CAL_MAX_BAND_3 = 255 QUANTIZE_CAL_MIN_BAND_3 = 1 QUANTIZE_CAL_MAX_BAND_4 = 255 QUANTIZE_CAL_MIN_BAND_4 = 1 QUANTIZE_CAL_MAX_BAND_5 = 255 QUANTIZE_CAL_MIN_BAND_5 = 1 QUANTIZE_CAL_MAX_BAND_6 = 255 QUANTIZE_CAL_MIN_BAND_6 = 1 QUANTIZE_CAL_MAX_BAND_7 = 255 QUANTIZE_CAL_MIN_BAND_7 = 1 END_GROUP = MIN_MAX_PIXEL_VALUE GROUP = PRODUCT_PARAMETERS CORRECTION_GAIN_BAND_1 = "CPF" CORRECTION_GAIN_BAND_2 = "CPF" CORRECTION_GAIN_BAND_3 = "CPF" CORRECTION_GAIN_BAND_4 = "CPF" CORRECTION_GAIN_BAND_5 = "CPF" CORRECTION_GAIN_BAND_6 = "INTERNAL_CALIBRATION" CORRECTION_GAIN_BAND_7 = "CPF" CORRECTION_BIAS_BAND_1 = "CPF" CORRECTION_BIAS_BAND_2 = "CPF" CORRECTION_BIAS_BAND_3 = "CPF" CORRECTION_BIAS_BAND_4 = "CPF" CORRECTION_BIAS_BAND_5 = "CPF" CORRECTION_BIAS_BAND_6 = "CPF" CORRECTION_BIAS_BAND_7 = "CPF" END_GROUP = PRODUCT_PARAMETERS GROUP = RADIOMETRIC_RESCALING RADIANCE_MULT_BAND_1 = 0.766 RADIANCE_MULT_BAND_2 = 1.448 RADIANCE_MULT_BAND_3 = 1.044 RADIANCE_MULT_BAND_4 = 0.876 RADIANCE_MULT_BAND_5 = 0.120 RADIANCE_MULT_BAND_6 = 0.055 RADIANCE_MULT_BAND_7 = 0.066 RADIANCE_ADD_BAND_1 = -2.28583 RADIANCE_ADD_BAND_2 = -4.28819 RADIANCE_ADD_BAND_3 = -2.21398 RADIANCE_ADD_BAND_4 = -2.38602 RADIANCE_ADD_BAND_5 = -0.49035 RADIANCE_ADD_BAND_6 = 1.18243 RADIANCE_ADD_BAND_7 = -0.21555 END_GROUP = RADIOMETRIC_RESCALING GROUP = PROJECTION_PARAMETERS MAP_PROJECTION = "UTM" DATUM = "WGS84" ELLIPSOID = "WGS84" UTM_ZONE = 45 GRID_CELL_SIZE_REFLECTIVE = 30.00 GRID_CELL_SIZE_THERMAL = 30.00 ORIENTATION = "NORTH_UP" RESAMPLING_OPTION = "CUBIC_CONVOLUTION" MAP_PROJECTION_L0RA = "NA" END_GROUP = PROJECTION_PARAMETERS END_GROUP = L1_METADATA_FILE END LT51420402011292KHCOO_MTLold.txt GROUP = L1_METADATA_FILE GROUP = METADATA_FILE_INFO ORIGIN = "Image courtesy of the U.S. Geological Survey" REQUEST_ID = "0101302267960_00007" PRODUCT_CREATION_TIME = 2013-02-26T14:05:07Z STATION_ID = "EDC" LANDSAT5_XBAND = "1" GROUND_STATION = "KHC" LPS_PROCESSOR_NUMBER = 0 DATEHOUR_CONTACT_PERIOD = "1129204" SUBINTERVAL_NUMBER = "01" END_GROUP = METADATA_FILE_INFO GROUP = PRODUCT_METADATA PRODUCT_TYPE = "L1T" ELEVATION_SOURCE = "GLS2000" PROCESSING_SOFTWARE = "LPGS_12.1.4" EPHEMERIS_TYPE = "DEFINITIVE" SPACECRAFT_ID = "Landsat5" SENSOR_ID = "TM" SENSOR_MODE = "BUMPER" ACQUISITION_DATE = 2011-10-19 SCENE_CENTER_SCAN_TIME = 04:42:07.7860000Z WRS_PATH = 142 STARTING_ROW = 40 ENDING_ROW = 40 BAND_COMBINATION = "1234567" PRODUCT_UL_CORNER_LAT = 29.7797312 PRODUCT_UL_CORNER_LON = 82.7943944 PRODUCT_UR_CORNER_LAT = 29.8358419 PRODUCT_UR_CORNER_LON = 85.3056144 PRODUCT_LL_CORNER_LAT = 27.8460446 PRODUCT_LL_CORNER_LON = 82.8714971 PRODUCT_LR_CORNER_LAT = 27.8978617 PRODUCT_LR_CORNER_LON = 85.3367692 PRODUCT_UL_CORNER_MAPX = 93300.000 PRODUCT_UL_CORNER_MAPY = 3301800.000 PRODUCT_UR_CORNER_MAPX = 336300.000 PRODUCT_UR_CORNER_MAPY = 3301800.000 PRODUCT_LL_CORNER_MAPX = 93300.000 PRODUCT_LL_CORNER_MAPY = 3087000.000 PRODUCT_LR_CORNER_MAPX = 336300.000 PRODUCT_LR_CORNER_MAPY = 3087000.000 PRODUCT_SAMPLES_REF = 8101 PRODUCT_LINES_REF = 7161 PRODUCT_SAMPLES_THM = 8101 PRODUCT_LINES_THM = 7161 BAND1_FILE_NAME = "LT51420402011292KHC00_B1.TIF" BAND2_FILE_NAME = "LT51420402011292KHC00_B2.TIF" BAND3_FILE_NAME = "LT51420402011292KHC00_B3.TIF" BAND4_FILE_NAME = "LT51420402011292KHC00_B4.TIF" BAND5_FILE_NAME = "LT51420402011292KHC00_B5.TIF" BAND6_FILE_NAME = "LT51420402011292KHC00_B6.TIF" BAND7_FILE_NAME = "LT51420402011292KHC00_B7.TIF" GCP_FILE_NAME = "LT51420402011292KHC00_GCP.txt" VER_REPORT_FILE_NAME = "LT51420402011292KHC00_VER.txt" VER_BROWSE_FILE_NAME = "LT51420402011292KHC00_VER.jpg" METADATA_L1_FILE_NAME = "LT51420402011292KHC00_MTLold.txt" CPF_FILE_NAME = "L5CPF20111001_20111231_06" END_GROUP = PRODUCT_METADATA GROUP = MIN_MAX_RADIANCE LMAX_BAND1 = 193.000 LMIN_BAND1 = -1.520 LMAX_BAND2 = 365.000 LMIN_BAND2 = -2.840 LMAX_BAND3 = 264.000 LMIN_BAND3 = -1.170 LMAX_BAND4 = 221.000 LMIN_BAND4 = -1.510 LMAX_BAND5 = 30.200 LMIN_BAND5 = -0.370 LMAX_BAND6 = 15.303 LMIN_BAND6 = 1.238 LMAX_BAND7 = 16.500 LMIN_BAND7 = -0.150 END_GROUP = MIN_MAX_RADIANCE GROUP = MIN_MAX_PIXEL_VALUE QCALMAX_BAND1 = 255.0 QCALMIN_BAND1 = 1.0 QCALMAX_BAND2 = 255.0 QCALMIN_BAND2 = 1.0 QCALMAX_BAND3 = 255.0 QCALMIN_BAND3 = 1.0 QCALMAX_BAND4 = 255.0 QCALMIN_BAND4 = 1.0 QCALMAX_BAND5 = 255.0 QCALMIN_BAND5 = 1.0 QCALMAX_BAND6 = 255.0 QCALMIN_BAND6 = 1.0 QCALMAX_BAND7 = 255.0 QCALMIN_BAND7 = 1.0 END_GROUP = MIN_MAX_PIXEL_VALUE GROUP = PRODUCT_PARAMETERS CORRECTION_METHOD_GAIN_BAND1 = "CPF" CORRECTION_METHOD_GAIN_BAND2 = "CPF" CORRECTION_METHOD_GAIN_BAND3 = "CPF" CORRECTION_METHOD_GAIN_BAND4 = "CPF" CORRECTION_METHOD_GAIN_BAND5 = "CPF" CORRECTION_METHOD_GAIN_BAND6 = "IC" CORRECTION_METHOD_GAIN_BAND7 = "CPF" CORRECTION_METHOD_BIAS = "CPF" SUN_AZIMUTH = 148.4288883 SUN_ELEVATION = 46.0128336 OUTPUT_FORMAT = "GEOTIFF" END_GROUP = PRODUCT_PARAMETERS GROUP = CORRECTIONS_APPLIED STRIPING_BAND1 = "NONE" STRIPING_BAND2 = "NONE" STRIPING_BAND3 = "NONE" STRIPING_BAND4 = "NONE" STRIPING_BAND5 = "NONE" STRIPING_BAND6 = "NONE" STRIPING_BAND7 = "NONE" BANDING = "N" COHERENT_NOISE = "N" MEMORY_EFFECT = "Y" SCAN_CORRELATED_SHIFT = "Y" INOPERABLE_DETECTORS = "N" DROPPED_LINES = "N" END_GROUP = CORRECTIONS_APPLIED GROUP = PROJECTION_PARAMETERS REFERENCE_DATUM = "WGS84" REFERENCE_ELLIPSOID = "WGS84" GRID_CELL_SIZE_THM = 30.000 GRID_CELL_SIZE_REF = 30.000 ORIENTATION = "NUP" RESAMPLING_OPTION = "CC" MAP_PROJECTION = "UTM" END_GROUP = PROJECTION_PARAMETERS GROUP = UTM_PARAMETERS ZONE_NUMBER = 45 END_GROUP = UTM_PARAMETERS GROUP = GEOMETRIC_VERIFY UL_QUAD_RMSE = 1.00 UR_QUAD_RMSE = 1.00 LR_QUAD_RMSE = 1.00 LL_QUAD_RMSE = 1.00 SCENE_RMSE = 1.00 END_GROUP = GEOMETRIC_VERIFY END_GROUP = L1_METADATA_FILE END

Landsat metadata files changed format last year. ENVI 4.8 is only capable of reading the _MTLold.txt file. ENVI 5.0.2 is capable of reading the new _MTL.txt files. You can find more information about the changes here: http://landsat.usgs.gov/L...Metadata_Changes.php