>I assume that the problem does have to do with the new version of the backup software--but I'm not sure in what way. It says you can work while it is backing up, and since the online backup took several days, I did that. Al suggested I review the event log and I notice that disk i/o errors began shortly after the online backup started, but there haven't been any new ones since I ran chkdsk. I restored the project I was working on from backup and it still won't compile, nor will any other VFP project. I reinstalled VFP and that didn't help. The error message appears at the point where type libraries are being created.
>
> I'm running out of ideas. I could restore C:\ but I'm not convinced even that will help.

I would try comping everything individually to make sure are the files are good:
compile classlib *.vcx
compile form *.scx
compile label *.lbx
compile report *.frx
compile menu *.mpr
compile *.prg
compile database mydatabase*

If everything seems to compile ok this way, then try compiling the whole project. Also make sure you have read/write permissions to the folder where you're doing this and that none of the files are marked read-only.