engine knocking?

i just took off my waterpump to fix a leak and one of the bolts broke that go through the timing chain cover and into the block. so i striped the front down and took the cover off, got the bolt out, then while it was off i replaced the harmonic balancer, and the timing chain. i got everything back together and now there is a bad knock on the drivers side. I was very carful about putting the chain back on and making sure the dots went back in the same place as they were before i took them off. how could this have happened
i guess after i unbolted the fan/pulley from the water pump (with the belt sill on) my room mate, who was working on my exhaust below, tried starting the car while i was inside and since the the water pump pulley was unbolted and just sitting there, it came off causing the belt to loosen and come off the other pulleys. would this have caused the problem?

-allan

im not sure, it was the one autozone gave me.

no shake, its just the knock.