> I tested with new "Firebird 2.0.1 (RC1)" and the error persists...

Hmmm... bad. The bug ID is CORE-1094 and according to tracker it was
backported to 2.0.1.

> Did you receive the test case that I sent to private e-mail?

Yes, but I had no time to test it. I hope I will have answer until
Wednesday.

Roman