Why doesn't my file properties have a compatibility tab on Windows Vista?

If The "Compatibility" tab is missing in Properties window, the problems is 2 system files "wer.dll" and "Faultrep.dll" are missing from "%windir%\System32" folder. Either the files were deleted by mistake or were not installed by Windows because of removing some Windows components from the setup.

The solution of this problem is very simple. Just download following ZIP file, extract it and you'll get both system files. Now copy the files to "%windir%\System32" folder. If you get overwrite prompt message, select NO.

As said before, only programs (applications, executables) need a compatibility mode. Those are the things on a computer that 'do' things and the computer needs them to be able to do those things. Some of them are written for older Operating systems and therefore require the compatibility mode to know what to do when a program runs. (the names of programs usually end with .exe and sometimes with .COM on windows PCs)

Files like word documents or images only contain information for programs, like word or paint, but don't do anything themselves. When opening those files, you actually open the program that is assigned to that file type (like .doc and .docx files are assigned to WORD.exe and .bmp and .jpg to mspaint.exe)

If you want to open those files in compatibility mode, you need to set the assigned program to this compatibility mode, not the file itself.

I hope this was clear enough. :)