Question : Problem: Defective Processor or Incompatible Processor???

I own the Asus P5N-E SLI, and I just tried upgrading to the Intel E8400 Core 2 Duo processor.  The most current bios is up to date, as well running Vista Business x64.  When I swapped out my Intel E4500, and replaced it with the Intel E8400, my machine started freezing on the microsoft corporation screen and the welcome screen.  Could this be a defective processor or an incompatible processor?  Keep in mind that Asus states this board can run the Intel E8400.

Answer : Problem: Defective Processor or Incompatible Processor???

CPU & memory timing issues can be very tricky to isolate and correct ... and can be the cause of a LOT of apparent incompatibilities.   Try adjusting your memory timings to a less aggressive setting.   Go into the BIOS, and add 1 clock to each of the memory latencies.  i.e. if it's currently running at 5-5-5-18, change it to 6-6-6-18.   See if that resolves this issue (it just may).