We had a '94 944 n/a since new within the family, now under my name. It's been very reliable, never stranded anyone, with annoying yet minor problems here and there (plus the AC, which I don't put in the minor category).

My brother drove it home without any warning or indication (so I'm told), it was parked for maybe an hour. When it was started again, the engine didn't sound right, couldn't shift out of park, ABS/SRS warning lights were on, none of the lights would work in 'ON' position (even though they work in other settings).
Using the 'unlock' key, I managed to shift into other gears, and in neutral, it made a very horrible screeching sound. Looking under the hood, one of the pulleys for the accessory belt had seized. I live in MA, so it's been cold for a while, in single digits to highs of 20's for over a week now.

It was disconcerting because I thought it was the car that'd bring us to 200k miles (currently at ~120) without stranding anyone. Everyone was home, so it was the best place to get stranded, but had to call for a tow truck.

My questions are :
- What is a 'seized pulley' exactly? I mean, I know it stops turning, but what causes that? Are there bearings? I thought it was the belt that turned the 'slave' pulleys.
- How common is it to have the pulley seize on you like this on Volvos? Other car makers? More prone in cold weather?
- Is there a way to somehow get it to seize more easily by driving/parking/turning off a certain way? I ask this 'cause my brother car, '96 SAAB 900 had the exact same problem a few days ago (seized pulley noticed upon restarting after an evening class), and he was actually on his way to pick it up after getting it fixed. I was joking to him that I now ban him from driving none of my cars until he drives out the demons in himself. Maybe he was a poor car mechanic in his former life.

What I think is somewhat funny is that the cars we have in the family ('96 855t, '96 964, '93 944, and '97 SAAB 900SE) are taking turns to break down on us, but only one at a time, and they have completed the cycle and starting over. One notable absence in the conspiracy is '94 Nissan Maxima, which I almost sold last year to get the 855t.