Word 2010 normal.dotm corruption?

I recently upgraded to Word 2010 and have had difficulties when opening multiple files (up to 10) and error messages with regard to normal.dotm. I have renamed and deleted the old normal.dotm but still the same difficulty occurs. This never occurred in my previous versions and I could open up to 15 files at once. (I open several documents at once to proof faster instead of clicking one by one.)

Here's what happens:

The dialog box that appears states: Cannot open existing file (normal.dotm). When I click OK it then goes away. When I go to close the document on the screen, another dialog box appears that reads: Word cannot save this file because it is already open elsewhere (C:\...Templates\Normal.dotm). When I click okay here, it brings up a save template dialog box. I have always been told on previous versions not to save to the normal template when errors like this occur so I click cancel. I now have have no document open but the Word application is still open. I then close it out (CTRL+F4). The final dialog box appears stating: Changes have been made to the global template, Normal.dotm. Do you want to save these changes? I click Don't Save. Then the next document opens.

How can I stop this error from occurring? No macros are being used and even if they were, they get deleted when I rename the Normal.dotm file.

Please help if you can. This is driving my batty.