|First thing to do is run a Diagnostic:|
Running Microsoft Office Diagnostics from within Excel/Word
Click the Microsoft Office button
Click on the Excel/Word Options button to bring up the Excel Options dialog box (at the bottom of window)
Click on the Resources button in the left hand pane
Click on the Diagnose button in the right hand pane
Click Run Diagnostics
See if that helps.
Aslo found this:
This is a bug in Excel 2007 when in page layout view.
Try changing the Zoom level slightly up or down a couple of percent.