Well naturally crashing isn't normal, but the very first time you do an update, there can be a *lot* of changes, and the updatedb process can take a pretty long time. After the initial one, the subsequent ones shouldn't take as long.
Also, when you say "it crashed", do you mean that the entire system totally locked up and you had to do a hard reboot, or just that the individual process seemed to just not respond for what seemed to be a pretty long time? I'd be surprised if it were the former, and if it were the latter, it may not be unusual. What are the specs of your machine? I can't offer any guidelines for how long it should take for a given PC, but if you happen to running, say, a P3 600Mz with 96Mg RAM it will take noticeably longer than if you're running a P4 3.0Gz with a gig of RAM. -- J.W.