I had a problem with MS Word not saving over an existing file. I requested help here
https://forums.comodo.com/defense_help/microsoft_word_doesnt_save_a_modified_file-t30870.0.html
but the answers didn’t help resolve the problem.
I didn’t mention an important fact there: the software involved was MS Office 2000
I now updated (after a total Windows reinstall) to MS Office 2003, and NO PROBLEM NOW, so I can use Comodo, HURRAAAY!
However, I believe it may be worth checking if Comodo is in fact incompatible with Office 2000 (unless there are people using it together with Comodo without problems, in which case my issue will remain a mistery).