I'm having a very weird problem here for the last few months. In Word, and in fact all programs from the Office 2007 suite, I can't drag the mouse pointer to select text.
I can click at a point in the text and the cursor moves correctly to that point. If I double click, the word under the cursor is selected, and triple clicking selects the whole line. However if I hold the mouse button down and drag the mouse, no text is selected.
Occasionally the problem disappears and everything works fine, but it then reappears a few minutes later. Text selection with the mouse works everywhere else (Firefox, PuTTY, OpenOffice), just not in Office.
The only addins are Google Desktop Office Addin, and Person Name ().
For info it is Office 2007 SP3, running on Windows 7 64-bit.