To follow up on this problem...

I have two copies of VFP 7, one with my MSDN subscription, and a separate copy that I purchased. I had only tried installing from my purchased copy (and on two different machines). Today I tried from the MSDN copy, and that one works fine. Apparently, there's something corrupted on the disk I purchased.

>>Something has happened to my version of VFP 7. When I open the form designer, and try to change the forms control toolbar to a class other than "Standard", VFP chokes with an error that says "The memory address can't be read." These classes will all open just fine in VFP 6. I've tried:
>>
>>Creating a new class in a new VCX
>>Running the Repair/Reinstall option
>>Compiling the class library
>>Completely uninstalling VFP 7 and reinstalling
>>Running VFPClean.app
>>With and without the three patches
>>
>>None of the above attempts have fixed this problem! Has anyone else run into this? Is there anything else I can try, short of reformatting my hard drive and starting over?
>
>In addition to James' suggestions:
>
>- run an up-to-the-second virus scan
>
>- do normal OS "housekeeping" tasks like cleaning up temp files, etc. Go out to windowsupdate.microsoft.com and apply updates.
>
>- run a RAM tester and check your RAM chips (or do a complete system hardware scan)
>
>If you have a known good system backup, you could restore that and see if it works or still has the same problem. If the problem persists you've likely got a hardware problem.