Calc: Paste button greyed out and not in context menu, but ctrl-v works?

When copying any information (text, cell or row) in Calc, the data is successfully copied to the clipboard, however the Paste button in the toolbar remains greyed out, and there is no “Paste” option in the right-click context menu. The CTRL-V shortcut works.

We are running LibreOffice on WinXP.

One thing to try is reset the user profile sometimes solve strange issues.