SQL vs DAO calculation in Access 97

Hi
I have a table T_AAA linked to a fixed lenght text file which is replaced every 2 weeks from a mainframe. 2 numeric (single) fields defined in there. Every 2 weeks I run a query to APPEND selected records from this linked text table to a nativeAccess table T_BBB with the same structure.
Then I run:
UPDATE T_BBB SET T_BBB.FTE = [FTE]/100, T_BBB.salary = [salary]/100;
and SOMETIMES (most of the time lately) I get an “Invalid Argumet” error.
I compacted and repaired – didn’t help.
Then I wrote VBA Update sub to do the same task and it did work. But my process requires SQL query, and I see nothing wrong with that query.
Please help me find a fix, because I’ve had related problems and VBA didn’t help.
Thank you, Serge.