I have a Dell PE4400 that has been crashing daily for the past few months. The debug and event log pointed at a possible bad processor. Dell dispatched a tech with a new processor and motherboard. The motherboard was replaced and all diagnostics passed. The tech departed just before it crashed again. After rebuilding it the second time I decided to bring up various applications and devices one at a time, and we found the problem; Our DLT4000 tape backup system, and Veritas Backup Exec 9.0/9.1 recommended using its own drivers! On the Dell website I found a copy of Backup Exec 9.1 in the DLT4000 tape drive downloads and installed it. Problem solved!