>>I have no idea if this applies to you, but I was having problems with ISOs on Win 95. I finally figured out what was causing it.
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>>In explorer, I noticed my "D" drive would apparantly randomly get mapped to a drive on the server that was already mapped to "S". I disconnected it because there was no need for it to be there. Then one day, I noticed the connection between me deleting the connection and the ISO. I looked at the shortcut the the app, and it had changed itself from the "S" drive to that mysterious "D" drive!
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>I only use UNCs in my app, so I don't think that's a problem. However, I just had another very important clue. I've been watching the vfp TMP files in the NT C:\Temp folder, and I just had something veeerrrry strange occur. One of the vfp temp files created when vfp or the app opened was called 4B070007.tmp
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>All of a sudden, the "Open With...what program?" NT dialog popped up with that file being the one NT couldn't figure out what to open with. Clearly, NT's losing track of file handles, something like that. Why on earth would it do that?

The "Open With..." dialog indicates that something attempted to indirectly open the file - an API call to one of the ShellExecute()/ShellExecuteEx() family of players got invoked, possibly through an accidental click action in Explorer, firing Shell.Application's Open method, or launching an InternetExplorer.Application object's Navigate method are some of the things that could be the root cause.