Very strange turn of events... today I went to open an old spreadsheet - something several years old. Excel opened it perfectly and when I was done, I noticed that there was now a jumplist entry for Excel on my start menu.

After playing with it for a while, it appears that any spreadsheet saved in the new Excel 2007 format (,xlsx) will NOT show up in the Excel jumplist on the start menu. Spreadsheets with the .xls (Excel '97-'2003) will appear in the start menu jumplist for Excel.

Oddly, all Word documents (.doc and .docx) appear fine in the Word jumplist on the start menu.

This leads me to a new question: why is this happening?