Wild guess: maybe the autocorrect is ON ?

It looks to me that you are storing data in the Field name.  Do you have of
the Fields with similar name, e.g. "Feb-05"

If yes, storing data in the Field name is a no-go zone in Relational
Database Design Theory.  Database engines cannot process data in names so
you will have lot of problems later with this structure...

Wups! Normalization Alarm Bells going off.

A field name should NEVER UNDER ANY CIRCUMSTANCES contain data. Any
table with a field named Jan-05 is *very* unlikely to be properly
normalized!

If your table is getting one field wider every month... it's not a
table; it's a spreadsheet. If you want spreadsheets, use Excel; if
you're using Access, consider a "tall thin" table with one record per
month, with a datefield.

That said - probably the suggestion of turning off Name Autocorrect in
the database's Tools... Options is the best bet.

                 John W. Vinson[MVP]