Question : Access 2007 text box using Sum function won't update until focus leaves Access window

I have an application that works fine in Access 2003 on Vista, but in Access 2007 on Windows 7, it won't display any data in a text box that uses the Sum function unless I click entirely off of the Access 2007 application window (for example to another application window or the desktop).  As soon as Access 2007 loses the focus, all of the Sum fields update properly.  If I change a datasheet value, the Sum field(s) that total that value go blank until once again I change the focus to another window.

Answer : Access 2007 text box using Sum function won't update until focus leaves Access window

Got it.  After importing into a clean database made no difference, I noticed I had a backup of the main form from 2005.  WHen loading it, I was prompted me for a date, but once I got past that, the Sum fields updated immediately unlike the current form.  It turns out I had a text box that referenced a subform that I had removed from the Main form 4 years ago.  Once I remove that text box, all of the Sum fields updated immediately.  

It's interesting that I never got an error about this bad reference.  And it's baffling that this problem only manifests in Accesss 2007 and Win 7.  go figure...

Thanks again for your help!