xp, excel and scroll lock

I still don't know why it does this, but it does it rarely enough for me to forget how to fix it.

Excel decides scroll lock is on, and won't allow cursor navigation of cells.  The little box on the bottom says "SCRL" in it.

The scroll lock key on the keyboard (with or without any combination of alt, ctrl, etc) does nothing.

Open up the on-screen keyboard, and click the 'virtual' scroll lock key.

Programs->Accessories->Accessibility->On-Screen Keyboard