Why do I have problems with selecting text by dragging my mouse across it? As soon as I leave the text in order to, for example, change the font the highlighting disappears and nothing changes in the selected text.

Unless there's a fault in your mouse driver, the only explanation I can suggest is a fault in Office itself. Have you tried repairing the Office installation (via Word Options|Resources|Diagnose)?

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

No, I hadn't tried that, this problem doesn't happen every time I try selection by dragging my mouse, but sometimes I have to have several tries before it eventually works. I couldn't find Resources|Diagnose on the Word options tab. - thanks for the suggestion anyway.

Are you using Office 2007, as your profile indicates?, If so, the Diagnose option should be there. Alternatively, you can repair the Office installation via Start > Windows Control Panel > Programs > Programs & Features > Microsoft Office (version) > Change>Repair.

As this doesn't happen all the time, are you perhaps using a mouse with a touchpad? If the touchpad is active when using a mouse, even brushing it slightly can change the selection. Most touchpads come with utilities to disable them when a mouse is connected.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]