Symptom: when you hit F1 to access help the cursor on the doc explorer window flickers continuously.
MSFT says it's a bug.
A workaround is suggested here, you switch options from "online only" to "Local first, then online", and remove the "Codezone" and "Questions" online targets. I found it works at first, but fails on subsequent searches.
Clicking on the scroll bar seems to work better, it stops the flicker in VS2008 Pro on my Vista box