I have checked out the IS pages on VB runtime support files, but they don't address the situation of the collection of cumulative roll-up files. A post on their forum merely resulted in a reply of "try it and see if it works." I like to be a little more considerate than that. Even if I thoroughly test my program (on Win95 for example) with the cumulative roll-up files and it has no problems, I am hesitant to change these files on a user's system if it may make some other vb6 program (which may use routines that mine doesn't)crash.