98 Belt problem

Hello all,
Z34, 3.8 Liter, 120,000 miles
I was driving on the interstate yesterday, about 60 mph, when my drive belt blew. Actually, it didn't completely blow, the belt was about half shredded. I was able to cut the excess off and get it home safely to put a new belt on.(The old was pretty worn) Took out for a test drive that night and it seemed fine. About 30 minutes into my drive to work today, the engine stopped. Finally, after a couple times of restarting, I got it started and got it off the road and looked under the hood. Everything looked ok, belt looked fine, everything seemed to spinning just fine.

Is there some other underlying problem here? Could something be locking up for a second and make the belt stop and mess everything else up? And since it was pretty worn yesterday, the thing that locked up could have just shredded the belt?

I can generally fix things just fine, my only problem is actually diagnosing the problem itself.

Thanks for the help!

check the a/c compressor. Look in the gap between the clutch and pulley face for metal shavings. If present, the a/c compressor is locking up either when engaging (it will operate regardless if the a/c is turned on if the HVAC is set to defrost or blend) or when disengaging (the bearing in the pulley that allows it to free-spin is bad). If the compressor checks out, look over the idler/tensioner pulleys real good. Any that have the slightest drag/scratchy feeling when rotated should be replaced.