"bootmgr is corrupt" error after upgrading my cpu.

[ay20]

hello,

i have a hp pavilion p6231fr with a motherboard ""m2n68-la Narra6 6.00A"".i used to have an AMD Athlon™ II X2 215 Processor and now i just purchased an AMD phenom II x2 555.Therefore,my new processor is detectable in Bios(AMI v 5.04-amd agesa v3.5.1.0 attached below) and the cpu speed/cache memory all stated there.Even when i do a hp smart test from bios, my processor is healthy 100%.
Now the problem occurs AFTER the bios,by simply giving "bootmgr is corrupted.failed to load the os",even with a bootable windows7 installation image.
i have a linux ubunto bootable image, and when i tried it, it boots and just freezes on the 1st 5secs of loading.
so my best explanation here, is that my bios is having issues with my new cpu altho it read it and accept it.
i will try to test my cpu with stresslinux just to be sure(since this new cpu i bought is used  ).
if anyone know a good bios modded with plenty of advanced options and settings, please share.
btw when i put back my old cpu , everything goes back to normal.