BleepingComputer.com: bum install of XP?

I recently reformatted my desktop and I have an interesting issue (well, several, but only this one that is really annoying)

Whenever I open nearly anything, I used to be able to use either the keyboard or mouse buttons to page up/page down. After this formatting, I have to click in the field before it will page up or down and it gives me a flashing cursor.

For instance, in firefox, I used to be able to open it and once the page loaded I just hit page down to scroll. Now I have to click on the page which gives me a cursor in the body of the page and then I can scroll the cursor. Sometimes it still won't let me scroll. It will try to scroll but instantly snap back. Tried three different mice and two different drivers, but the fact that its the same with the keyboard and the mouse, and its the same with FF, IE, Adobe, outlook express, and all other programs suggests that its something with XP. Thoughts on how to fix?