well, i'm sure where to start so... yesterday i was riding to class and my chain loosened up a lot for some unknown reason. i attributed it to the QR, even though i haven't ever had any problems with it, and just loosened the back wheel, made sure it was all the way back in the dropouts, and that was that.

the tension was fine today, but then my drivetrain started making a squeaking noise that i can't figure out. i recently degreased and lubed my chain, so i thought that maybe i hadn't lubed it enough. after putting more lube on it, and letting it sit for a couple hours, it's still squeaking. it's hard to pin-point the origin, but it sounds like it might be coming from the back wheel. can anyone help me with any ideas of what it could be? my hubs have sealed bearings, but could they be messed up? that's the only reason for the problem that i can think of at the moment. any help would be appreciated.