Exactly the same behaviour on my x86 Win32 (XP home) machine. You're a champion Darren!
I assumed I'd be stuck with this corrupted forever when latest update made no difference. 8)
Hi
update installed
20110928-windows-x86-module.zip
Release date : 2011-09-28 00:00:00
Using the default - Ms Sans Serif 8pt font - still get corruption
change font to Tahoma 8pt and fixed 
many thanks
