Can't pinpoint my problem

I just bought a E8400 and installed it today in my P5B-E (upgraded from E6400). I installed BIOS revision 1802 through EZ flash because i hadn't updated since before the 45nm's came out. I reset to all default settings on my mobo. Unfortunately, when booting up, windows bluescreens before the loading bar comes up when using the e8400, but while booting up with the e6400 on the new bios everything works fine. (I even installed the bios and reset the settings again while the E8400 was in the slot to see if it would make a difference, it didn't)
After windows bluescreens and restarts, the p5b-e startup splash comes on like always, but nothing else happens. I have to unplug my computer before it will attempt to boot again. I am confused as to what could be causing this, and I'm out of stuff to try.

+1

new bios means you need to tune it
check the memory settings and voltage

While I would agree with sarwar_r87 if this was a motherboard swap, I'm not sure that it's necessary with a CPU swap. Especially since both CPU's are dual core. A windows install would definitely be required if your were going from a single core to a dual core, because you would need the version of hal.dll for ACPI Multiprocessor. This is not the case, and there are no drivers for Intel CPU's.

Ghost, when you cleared the BIOS, you said it boot into Windows fine the first time, but then on a subsequent reboot, it didn't. Did you change anything in the BIOS in between the successful boot and the unsuccessful.

Which Windows are you running? I have been assuming XP, but could you specify. Did you have any custom setting in your BIOS pre-upgrade, such as a specified voltage for your RAM, etc?

Let us know.