Have you tried resetting the view?
Look in View } Current View | Customize Current View ... Reset.

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Bill R MVP
"anna" wrote in message
news
I highlighted the first row of numbers on one Micorsoft Office Outlook
calendar and accidentally hit the backspace button. All the gridlines
throughout all of my Microsoft Office Outlook calendars now have a white
line
(no gridline) next to every single number. Undo wasn't available. The
remainder of the gridlines are there in black. I have rebooted,
reinstalled
Office and updated Office 2003. I can't get that part of the gridline to
change back to black. Easy mistake to make...no easy fix found.