OK, I've talked about this before, and I finally got a hold of the pictures. Check em out here
OK they aren't paintball tanks, they are firemens SCBA's, but the designs are very similar, and the reason they can be dangerous is the same for both, they are fiber wrapped.
The only information I could get about why this tank blew up is that it was exposed to a cleaning material, the guy I talked to said he thinks it was armoral, and that it really weakens the fiber wrap.
Anywayss I'm just trying to let you guys know, don't expose your tanks to anything but air, paint, and water, never know what could make it blow.