I have VFP6 , SP4 . I saw that SP5 is on stage, so I'll download it , too .
This error appeared in the last 1-2 weeks. Last time happened when I pressed ALT-TAB to Winamp , then ALT-TAB back to VFP . I don't know if this is exactly the reason , I only think so . I pressed the same keys again and nothing happened, so ...
Perhaps my SO needs a reinstallation ...

Mihai