PC: HP a1100y OS: XP sp2 Upgraded Celeron D to Pentium 4 After CPU the processor was installed I attempted to boot normally and the 1st time it worked - but Windows said "you may need to restart your computer for hardware to perform properly [paraphrasing]" so I restart... Now when I select "Windows XP Professional" attempt to boot normally it just restarts the PC. It also does this in SAFE (and SAFE with Cmd, Ntwrk Prompt, etc.) It just so happens that I use an app called TuneUp Utilities and there's an option during startup for "Windows XP Professional (TuneUp Backup)" which I tried when all else failed (Last Known Good, etc) and it boots just fine. My question is: How can I repair XP so I can boot normally? I've tried checking the disk(s) but not much help, and while there's a lot of folks offering different solutions (repair install, or god forbid- fresh install) I thought that my ability to boot through TuneUp might offer a clue as to what's ailing me. Thanks for any help

Does the BIOS have to be reset to defaults when the processor is changed or is that automatic?

What was the point of upgrading the CPU in the 1st place? http://h10025.www1.hp.com/ewfrf/wc/... "If my answers frighten you then you should cease asking scary questions" - Jules Winnfield (Samuel L. Jackson) in Pulp Fiction

@ guapo: I pulled the Cmos battery & reset BIOS when I did the swap - looks like I might need to fix the mbr. @ jam: The point? Well, I wasn't trying to really prove anything - you see I had this one cpu already installed, then I thought maybe a larger L2 cache + HT might give a slight performance boost, so I installed another cpu possessing these attributes. Sure enough it is faster than the Celeron. (what was the 'point' of posting my MB?) Thank you :)

You still might want to go into the BIOS and check the settings.

Thank guapo, But I manually configured BIOS (after reset) to it's proper settings - and am able to boot right into the OS menu, it just that XP won't start normally (unless I boot into the TuneUp BackUp). Now some (most) would assume this is a case of corrupt boot files, but after running the Recovery Console from the XP disk (where I attempted FIXBOOT & FIXMBR) I'm still not back to norm. Oh well... Thanks anyways. Gonna try Fixboot/Fixmbr first, se if that does any good. [If I perform System Restore I'm able to boot into XP normally - until Windows installs the new drivers for the CPU - then when I reboot I'm back to square one.]