Thanks for the replies.

I contend that this is a VFP bug. I base this on:
1) Only a few people seem to know "why" or "how" this could happen.
2) It is it not documented in VFP help
3) This NEVER happened in VFP6 OR VFP7.
4) The code this is happening in is standard, fully tested VFE framework code and code that ran fine under VFP6/7.
5) I still can't reproduce this myself, no matter how hard I try. It just shows up in production app error log.

Therefore, I'm not just going to go sticking GO TOP/GO BOTTOM in there somewhere in the hopes of it fixing what I consider to be a VFP bug. What you are describing as causing the problem I can't see any connection to where/when/how it's happening in our app. We are not inserting from custom event code, etc. The callstack shows the user clicked on the toolbar New button as they do hundreds of times a day without error. Sometimes the error occurs on a REPLACE in our save_pre and sometimes it happens in the new_perform method on the actual INSERT.
There is a grid for this form on the List tab. On activate of this tab, users are forced to save any pending changes or cancel navigation to the list itself. It is a read-only grid. Therefore, the buffer cannot be dirty while on/in the grid. I've tried every combination I can think of to make this happen in our app based on what I've read. I can't. I've read how to reproduce it by creating a new form with grids, etc. but that doesn't help me fix the app as I see no connection between the two.
If I find out any more info, I will post here.

Thanks,
Randy