2007 vs 2003 - error message in trying to run query

[sgtSortor]

I have been upgraded to Access 2007 this morning, and all of my databases that I created in A2003 are giving me problems. When I try to run a query that has criteria looking at another form that is open, but hidden in the database. I keep getting the error message

" is not a valid name. Make sure that it does not include invalid characters or punctuation and that is is not too long.

If I go to a co-workers computer that is still 2003, that query works just fine.

HELP!!!!!!