Dear Justin, It seems to be that in the past (2003) a version of Red Hat (version 8) was causing conflicts with the version of Adobe Acrobat that was shiped on the IDL 5.6 CD. In that case the solution was the following: To use on-line help with the IDL-DE, launch IDL with the command: env LANG=C idlde It could be possible that your problem is related with this case even though you are using a different OS. Try to launch IDLDE in this way and let me know if this fixed the problem. Greetings, Fernando PS. The following paragraph was release by RedHat 8 notes: "Certain third party applications, such as the Adobe(R) Acrobat Reader(R), may not function correctly (or crash upon startup) because they lack support for Unicode locales. Until third party developers provide such support in their products, you may work around this issue by setting the LANG environment variable at the shell prompt to C prior to typing the application name."