Could be a video driver issue.
Slide down the acceleration down on your adapter, control panel, display folder,
settings tab, advanced button, troubleshoot tab.
If the lines appear, go to the adapter manufacturer's web site and look around for an
updated driver.

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Mary Sauer MSFT MVP
http://office.microsoft.com/
http://msauer.mvps.org/
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> The gridlines on all my tables have disappeared, but they still print and
> appear on Print Preview. This was after I updated Office XP. Checking
> View>Boundaries and Borders does not make them reappear. Is there a default
> button For this that I may have messed with and forgot. Help