>On the install CD of my VP6 application I have included a number of .dll files, as suggested by others on this site. In a few cases these .dll files are newer than the customer's, so they overwrite the customers .dll's by the same name. Problem is, the customer has some older applications (WordPerfect, Lotus, etc) that won't work with my newer .dll files. My application won't work with the customer's older .dll's. What is a professional solution or explaination to the customer in such a situation? TIA.

Depending on what the .DLLs are, and how they're called, you might be able to specify that they be installed in the same folder as your app, rather than in a WINDOWS/SYSTEM folder. That way the newer versions should be specific to your app.