> AFAIK the problem was that FB allows one to delete a record from
> a dataset while accessing it within the same transaction. Is this right?

Not sure. I will re-read whole this thread to better understand your
access pattern. BTW, what kind of engine do you use - SS or CS ?

> If it helps I can send a zipped db containing the corrupt table/index
> (the size is about 3MB).

Do it please. If you will send it via e-mail then change (or just cut)
file extension else SF will not pass it. Or, if it is possible, send me url
pointing to download location. Or you can create ticket in our bug
tracker and attach your zipped db there if it is appropriate for you.

Thanks,
Vlad