Not common, no. I've never had Fallout crash (at least that I can remember) since it came out.
OK, good to hear that. I'll just hope the crash I experienced was a rare exception.
Usually "looping music" is a sign of a sound-card error or glitch which often force a black-screen and the need for a hard reboot.
Somehow I doubt it's a sound card problem. I've got a Creative X-Fi card and so far I've been very happy with it and never really had any problems in other games. Actually, when the game hanged, I thought I was experiencing the well known "black screen" Fallout problem (some users reported random "blackouts" while playing which are easily cleared by pressing 'C' or 'P'), so I simply pressed 'C'. That didn't help, of course, but I heard some short sound in response to that (I probably wouldn't have heard it if the sound card driver had crashed). Also, I didn't have to do a hard reboot - killing the Fallout process was enough.
And I hate to even ask/suggest it--but as you may know "illegal" copies of games are often very prone to such crashing and general lack of stability.
Actually such cases are extremely rare if you use content from well known sources (there are exceptions, of course, but they're just that - rare exceptions). I risk being modded down for this, but I'll tell it anyway - the paradox is that in many cases cracked content is simply more convenient to use for the end user compared to legal content and games are a good example of that. I'm not advocating piracy at all, but in my opinion, all the draconian copy protections some companies use only make life more difficult for their customers, not pirates/crackers.
Anyway, this does not apply to my case.