>>With Windows XP, I searched for "extensionhandler" in files in VFPSource directory to see if I missed any references. Well... none show up, even though I know there are at least some there, I closed any VFP session that may be using file.
>>
>>What could be the cause?
>
>Several files extensions are excluded in the search.

Thank you for your answer, Naomi.

The file specification was *, so I don;t think this is the problem.

Just downloaded the utility recommended by Sergey. Sure enough the strings were there, but no new ones. Good utility.