http://www.keil.com/forum/59677/
I've seen uv4 do this too, it's an odd focus issue, usually cleared by punching up/down a couple of other apps/windows
Win 7 x64 Pro AMD Catalyst (Radeon HD 4250 Graphics, 8.710.0.0 2/10/2010, ATI via MS WHQL) 1920x1200