rebooting all the time; can't get into WinXP

using tictac's D23 fire bios...was working fine but now i get constant reboots when trying to get into windows...goes thru standard post stuff but won't go into windows...can't go in in safe mode, even tho i can select it...reboot again...any ideas? alreadt tried resetting cmos, failsafe & optimized defaults, upping vcore and vdimm...waiting with the battery removed right now? is it my hd or windows? thanks all.