Jennifer,

Here are some wild guesses:

*.xlb file. If you have used Excel, you have a *.xlb file.  You need to
search again to find it and delete it.  Try searching from your C drive on
down.

Also, try the following:

Start | Run.  You do need to use the quotes and the path might need to be
modified to suit your PC.

"C:\Program Files\Microsoft Office\Office\Excel.exe" /unregserver

then do the same thing, but type

"C:\Program Files\Microsoft Office\Office\Excel.exe" /regserver

Also, try cleaning out the Temp folder.

Let us know how you make out with the new PC.

Best regards,
Kevin