>all normal error msgs in VFP 6.0 such as "invalid path or file name" for invalid command (such as: CD NEWDIR for invalid directory) in command window aren't producing normal foxpro dialog error box but just show ".F." on screen. Any ideas? Don't want to reinstall VFP with service pacs if possible.

Sounds like you have some code linked into VFP to override the normal error handler. Try issuing an ON ERROR all by itself from the command box to clear it out.