As any one purchased their macbook pro recently like in the past 2-3 weeks? and noticed these lockups and beachballs?
Mine is only 1 week old, and came with 1.7 installed. Tried to put an older 320gb drive in to install snow leopard, no dice. It would read very slowly or not at all. So I assume that's the same issue people would have if they upgraded a working system to 1.7.
Still seems to be a problem. The stock 250gb drive that the machine shipped with works fine, even under 1.7, so I'm just using that for the moment.