Is the reference to the excel sheets still open? I had a similar problem to the one you are seeing and I could get rid of it 2 different ways. The first is to make sure LabVIEW is entirely shut down. The second is to make sure you close the spreadsheets or dispose of the reference. These are workbooks that are essentially open in the background, so when you open excel they will show. Try either closing labview or the references to see if this helps your problem. Posting your code would also help.
