Thanks Al. You are right it is alias of the open table. And I had re-created all the indexes.
The interesting thing that I am in the process of the debugging a new application and this code was working perfectly. When error happens I would suspend and select ignore to step through my code in the debugger trace window. It will go through the same line of code again with no problem. I found if I would select the table to be in the current work area just before execution of the SEEK() function it fixed the problem. But the fact that I do not understand the nature of the problem makes me nerves. Thank you again
Yelena