I am experiencing this condition in the Extreme.
I too, believe it is only with Win7 (I run XP on a seperate partition and haven't noticed it there,) but I'm not sure.
I've been a hardcore fan of SB since the 2.xx versions but I am using anything BUT SB right now because it's so difficult to read.
The issue seems to have a timing componet as well; as text becomes blurry over a short time and sometimes clicking or otherwise bringing a page into "focus" will "re-focus" the text, but not for long. i.e. mousing over certain text areas brings them back in focus. But not always and not for long.
I tried changing a multitude of controls in the Security and Advanced sections of IE Internet Options as well as changing the default fonts. I initially thought it was an accessability issue relating to the "carat" that is refered to in the "accessability" area of advanced internet options. I've also upgraded and downgraded my SB versions up to current (7.01 ?) and down to (5.4 or 5.
(I'd have to check).
How far back (or how low a version) can I go that will still support Win7?
Any other suggestions GREATLY Appreciated.