I'd start by cleaning your system, for a safe registry clean use "toni arts easy cleaner" or if your comfortable use ccleaner,then right click on my computer,clik properties,clik on advance tab,clik on the settings button in performance,clik on advance,clik on virtual memory "change" button,tick the box "no page file" and apply,if you use hybernation disable it,then boot into safe mode and defrag,after defrag re-apply page file,go get any updates from microsoft,IE7 has also been updated to IE7 1RC (i think it's 1RC,no matter it's been updated).(disabling page file and hyber will give you a proper defrag since neither can be defragged while applied,it's what the unmovable files are)
Would'nt hurt to use star central and updte wb5 if not done already.
IE6 is still installed so when in add/remove IE7 will automatically put IE6 back.
Have you installed any plugins into IE7 recently there could be a clash,apart from a driver that's all i got,apart from previous poster asking does IE7 work if wb disabled,in any case defrag now
EDIT: go to lavasoft and get their free spy scanner then go get "spyware terminator" it's free also and does a better job than windows defender and is also a real time scanner and won't affect performance also do a virus scan but make sure all scanners are updated http://www.spywareterminator.com
