I managed to solve the problem I had by running xmllitesetup.exe as explained in some comment in john's link given above.
BTW, I have Google Desktop Search and it is not causing any problems with IE7 beta.
I have to say that aside this minor issue I had, IE7 is an improvement, although there is no way it will become my default browser any time soon. Why? (a) lacks a fully customisable layout like Opera does, (b) I have yet to see how standards-compliant it really is, and (c) it is windows-only, and I like tools I am able to use the same in various platforms, as I am a multi-platform user. This last one is the most strong reason, as this is not expected to change in the future. Can you imagine IE for Linux? I can't.
My choices? Firefox/Mozilla (too slow) and Opera (my preferred one).
Glad to see I am not the only one experiencing problems with IE7b2. Mine didn't exactly crashed, but the tab-bar is not visible. And believe me, I've done everything humanly possible to set it visible, and I couldn't. When I open a link in a new tab, the page goes front and I have no way to go to the original tab, except by pressing CTRL TAB.
I absolutely agree with you: bugs as simple, evident and easily reproduced as these ones should not be even thinkable in a product at this stage of development, and from the biggest software maker in the world.