Excel Problem using IE8

[mjklunk]

I inadvertently upgraded my browser to IE8.  The result of the mishap is that Cognos cannot complete the conversion of Excel reports.  All other formats work fine.  I know this has to be a browser setting issue (or perhaps Excel).  I can get Excel reports to run ONLY by holding down the Ctrl key until the report completes.

Anyone here know what settings I need to change and to what?

Thanks for any help you can give me.