I am getting "Visual Fortran run-time error" while performing atmospheric correction using FLAASH tool. The next line of the message is "forrtl severe (9): permission to access file denied, unit 20, file H:\ITT\IDL71\lib\hook\acc_modroot.mc". I'm using ENVI 4.7 on WinXP SP3 32 bit machine (Sensor specification: Unknown Multispectral; user defined filter function, wavelength and calibration). Any suggestions?