Some interesting methods here- http://jamesisin.com/a_high-tech_blech/index.php/2008/03/keyboard-input-ignored-for-c-h-t-and-v-keys-in-specific-applications-only/

This link is an older one based on Windows XP but has a nice list of different things to try and mentions that it doesn't appear to be an XP only problem. 

More hints can be found by Googling "my h c v keys don't work in Microsoft Word" 

No hammers are mentioned as cures but I'd be tempted if it wasn't an easy fix. She might even try Apache OpenOffice for at least the short term if she finds that it is ONLY in Word that there's a problem, which is a free Microsoft Office alternative that I use.