It sounds like something in the query is corrupted, so that Access cannot
display it correctly, even the the SQL executes successfully.
To solve the problem, try this sequence (in order):
1. Make a backup copy of the database while it is not in use, in case
something goes wrong.
2. Uncheck the boxes under:
Tools | Options | General | Name AutoCorrect
In Access 2007, it's:
Office Button | Access Options | Current Database | Name AutoCorrect
Explanation of why:
http://allenbrowne.com/bug-03.html
3. Compact the database:
Tools | Database Utilities | Compact/Repair
or in Access 2007:
Office Button | Manage | Compact/Repair
4. Press Ctrl+G to open the Immediate Window.
Enter this, substituting the name of your query for Query1:
Debug.Print CurrentDb.QueryDefs("Query1").SQL
When you press Enter, Access should show you the SQL statement. Copy it to
clipboard and paste it somewhere safe (such as in Notepad, and saved as a
text file.)
5. Delete the bad query.
Compact the database again.
Create a new query.
Switch the query to SQL View (View menu.)
Paste the SQL statement in.
Switch back to Design View (View menu), and arrange things as you wish.