Robert,

Try this:

Create a class which is at the same level as the
class which lost it's code. That is, they should
have the same parent.

Then add some dummy code, then save it. See if that
brings back the code in the sibling level class.

I'd be interested in knowing if it works. I encountered
the same problem in VFP 5.0 about a year ago, and strangely
enough, that fixed it each time.

Good Luck!