I forgot to add something: if I boot with a CD, I can also reboot without any trobule... unless I enter to the Windows XP installer.
What do you think could be the cause? BIOS? Motherboard? Hard Drive? Windows? How could I get rid of the problem?
I didn't know I had to post here instead of the Q&A forum. I apologize and I'll just copy and paste what I wrote there a couple of days ago.
Yesterday (in fact, Monday), I replaced my old Pentium 4 1.6 GHz Williamette with an AMD Athlon 64 bit X2 4000+ (I think it's a Brisbane), and thus I had to swap my ASRock P4VM800 with 2 x 512 MB RAM (generic) for a MSI K9MM-V motherboard with a Markvision 1 GB RAM stick. Anyway, I installed everything, and it all went fine... until I decided to apply the dual-core hotfix for AMDs.
During one of the required reboots, my computer froze at the POST: It didn't want to start the memory check... not even the processor check. The only workaround I've found is to shut down the computer, unplug the power source, plug it again and then boot the computer. Then it works perfectly.. until I decide to shut it down again, or I want to reboot it. If I don't cut the power supply off and then reconnect it, the computer will freeze at the POST.
I've tried clearing the CMOS, updating the BIOS, uninstalling the hotfix... but nothing, the problem is still there. And I've discovered something weird: If I boot from a disk, I can reboot without any trouble. If I let the computer boot from the hard drive (and thus Windows XP starts), I'll be getting again the reboot problem.
I'm using Windows XP SP2 (in Spanish), my video card is an eVGA GeForce FX5500, I also have 2 hard drives (1 IDE where Windows and all apps are installed, and 1 SATA for all the data, music, photos) and a DVD ROM drive (I had to sacrifice the CD-RW one due to a lack of IDE slots).
Does anybody know what to do? I'm not willing to face a 1-week downtime while I return the board to the store and they send me a new one (yes, I bought it on Internet because here at my city, the computer stuff is too expensive).
Best regards from Colombia