I have a Dell T 3500 , which has the PB 12 issue . I have on 4 occasions recovered the machine to working state . Does anyone have experience of this problem , in this model , and can shed light on what caused the problem . Contrary to all I have read on-line it is not a terminal problem , at least in my machine . I am though , desperate and persistent with a focused ( some may say obsessional ) desire to fix what I cannot replace . After recovery the machine can go into sleep mode and restart AND also shut down and restart ( But not an overnight shut down , as I found out yesterday ) . Has anyone else , after a PB 12 , 1 + 2 error , regained use of the machine ? Any thoughts much appreciated .