Runtime Error Message 217

I recently upgraded to IE 7, and to be honest, it's working fine with this one exception.

When I close IE after having multiple windows open, I receive the following error ...

and when I close that message box ...

This is not causing any performance issues with my system at all. I can re-open IE 7 at any time and it works fine. It's just annoying, and more than likely a setting issue.

Any suggestions would be appreciated.

System Description:
CPU Type Intel Pentium 4, 2600 MHz (13 x 200)
Operating System Microsoft Windows XP Professional
OS Service Pack Service Pack 2
Internet Explorer 7.0.5730.13
System Memory 1536 MB (PC3200 DDR SDRAM)
Video Adapter RADEON 9550 (256 MB)
3D Accelerator ATI Radeon 9550 (RV350)