Microsoft recently invited me, by way of an upgrade, to install version 7 of Internet Explorer. (Gasp, yes, I do use this browser, quite simply because I have to due to the requirements of certain software vendors).
In typical MS fashion,
it kept on crashing.
(That even rhymes)
I was invited to send MS the accident report.
They then told me the problem was not with them (it never is) but with Yahoo!'s toolbar. Once I had downloaded the latest version of Yahoo!'s toolbar, the problem seemed to have resolved itself, well, for now, anyway.
So, the moral of this story is, if you install Explorer 7 and it crashes a lot, check if you have the latest Yahoo! toolbar.