Oh wow. I'm still on XP and there no such setting exists (still happy with the old, crusty, but incredibly sharp winXP bitmap fonts <3 )
If this really fixes problems then this might be some weird ass bug in win7? The game doesn't use any windows-internal font rendering to my knowledge. It uses FTGL for fonts which in turn uses FreeType2, this is the only thing that could be affected by the DPI setting. Haven't ever looked at the FreeType code, no idea to which extent it uses the windows API. Really puzzled now...
But thanks for digging out a possible solution for rendering failures, things like this are impossible to track down...
EDIT: Thinking about it, afaik the included freetype was never updated (since ~2008). I'll update this and FTGL before releasing the next updatepack. Hope that'll help.