Not specifically kevs, but had recent problem with IE7 and Firefox both not opening the page and not allowing exit in Vista.
My problem turned out to be virus/trojan that Nod32 would not pick up. Switched to Karsperski trial and it picked them up straight away up. Took off systen restore and did safe boot and ran anti virus again. No problems since (apart from Vista which is about to revert to XP - much gnashing of teeth...).
Suggest you do virus etc check to be sure, if you have not done so aready.
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