That's a tough one that I haven't experienced. I take it that even a blank workbook has the problem.

I would start by removing any files in the xlstart folder. Any files in this folder are automatically opened when you start Excel. Where that is depends on which version of Windows you are using. The following are the usual spots.

In Vista: C:\Users\user name\AppData\Local\Microsoft\Excel\XLStart

In XP: C:\Documents and Settings\user name\Application Data\Microsoft\Excel\XLStart

From Excel help, here's how to find the folder:

1. Click the Microsoft Office Button, and then click Excel Options.

1. Click Trust Center, and then under Microsoft Office Excel Trust Center, click Trust Center Settings.
2. Click Trusted Locations, and then verify the path to the XLStart folder in the list of trusted locations