Marc
I had this issue a while back and it turned out that it was a setting in Excel that caused the issue - however I believe that we addressed the issue in v5.1 (and likely in one of the 5.01 or 5.02 patch updates - however this was the issue
In Excel, in the lower Right corner there are these three settings buttons
Open a Blank workbook and make sure that it is setup as shown above with the left hand button highlighted - I cannot remember now whether mine had none of them highlighted or one of the other two, but however I got mine like it was it prohibited the reports from generating.
If this fails, then I think you may have to reinstall TBC after updating your Excel Installation to clear your issue - can you try that and let me know if that helps
I tried to reach you on your other question and left you a Voice Mail
Alan