I had a similar problem in the past. Ever since, I use a brass hammer and torque it off, and then torque it back on when I'm done. Before re-installing though, i use anti-sieze on the bolts. Never had a problem since.
2000 CSVT Silver Frost: #942 of 2150
HID Projectors and Fog Light Mod, Optomized TB, MSDS headers
2003 Silverstone Z