>In general, it's not recommended to use filtered recordsource for grid. The reason is that it will be slow. You problem seems to be different. It may happen that you used some variables in filter expression and they go out of scope somewhere. Anyway, try to use more generic (non-filtered) approaches building your grids.

Edward,
You are certainly right with that (that filtered table is too slow for grid). However, I don't know how to solve this task otherwise. The user has to be able to filter (in this case) certain records which he then can edit like in a spreadsheet. Though I'd have liked to use SQL-Queries as recordsource, but the writing to the table then would slow down everything else, using much code to find out what the user edited and to find this record in the table and update it there... Huh, any other idea?