My class methods are just disappearing!

I open the class and go to the properties window and click on the methods tab and all my methods that I have created have disappeared. So I close the class and reopen it and they reappear. Sometimes I have to reopen it three or four times and they will finally reappear. I did make the mistake of saving when the methods were in the "disappeared" state and I lost them for good.

Can someone tell me what might be causing this?

At first we thought it was something specifically that I was doing. Then one of the other programmers encountered the same problem at his home computer. Different computers and different operating systems (NT and 98) and different libraries and different projects.

I am unable to recreate the problem consistently. I do check my methods now every time I open a class just to be sure they are there. And sure enough, every once in a while, they are gone. So I close the class and reopen it and the methods return.

We are running VFP 6.0 with SP3.