Can't paste in Excel97 worksheet

[BrianG]

I have an Excel97 workbook containing three sheets. I have been using this workbook for years but noticed this morning that I can't paste in one of the sheets. This situation may have existed for awhile since I rarely have had a need to modify anything in the sheet. I can copy and paste to, from and within the other two sheets but in this one sheet the paste and paste special commands are grayed out. I have checked to insure the sheet is not protected and even unlocked all the cells although this shouldn't affect anything since the sheet isn't protected. I tried copying the sheet to a new book but still can't paste.

Any suggestions on how to fix this would be most appreciated.

BrianG