Game-breakin' battle-bug!

[Monteef]

I've got the English version of KB: AP running on my wife's PC (Steam version) and she's run into a weird bug in combat. Sometimes, seemingly at random, the cursor will switch to the question mark "inspect" cursor, and no matter what she does she can't make her troops attack. Nor can she use the dragon or her spells - the only thing the cursor will do is inspect.

Any idea what's going on? Is there a hotkey or something causing this, or is it some kind of bug? She's got a pretty stock-standard 3GHz Dell with 3 gigs of RAM and a 32-bit OS (Win XP), so I doubt that's causing the problem. Thanks for your help in advance!