Thank you Jazz, I ended up finding the answer.
The scroll worked fine in all my applications except Excel 2007 and Word 2007.
In case anyone cares, here's what I did to fix it.
I went to Control Panel
clicked Printers and other Hardware
clicked Mouse
chose the Wheel tab
In the top section, there is a button labeled "exeptions", I clicked this
A pop up window appears where I can add applications
I clicked Add
The next window has 2 boxes. In the first box labeled Application Name, I simply typed in the "excel". The 2nd box is labeled Program Path. I clicked the browse button next to it and went through my C: drive Program files folder until I found the Excel.exe file and chose this and clicked Open and clicked OK.
I repeated this for Word
then I clicked Ok to finish the Exceptions window
Then I was back on the Mouse Properties window, I clicked Apply and then OK.
I shut down excel and reopened (not sure I needed to do this, but I did it just in case)
And the scroll worked again.
Same in Microsoft Word 2007
And these steps could vary depending on the version of Windows and how your control panel is laid out.