Hi xanderthemighty. I'm suspecting a hardware problem, but it could be one of several things.
Since you removed the CMOS battery you need to boot to the CMOS BIOS utility and make sure the settings are proper. I have never seen a BIOS that didn't need some adjusting after a reset.
Set or verify the time-of-day and date.
In the Boot Devices menu make sure that the optical drive is in the list before the hard drive.
There may be a setting regarding enabling SATA devices, or setting SATA to the preferred hard drive interface. I suspect that this is why your hard drive is not being detected, though it used to be before the BIOS reset.
First, I don't suspect the optical drive because it consistantly loaded XP each time without detecting errors. The problem occurred during the initial startup using the hard drive. I also don't suspect the motherboard because of the same reasons.
OK, about other hardware problem possibilities:The hard drive may have problems.
Download the drive diagnostic from your PC's hard drive manufacturer.Your BIOS can probably tell you who made the hard drive. They should have a diagnostic that runs from a bootable CD or floppy. If there isn't one available for download, burn and run the Hitachi Drive Fitness Test (DFT). You need to burn a CD with their ISO file. You will need a program such as Nero or Active ISO Burner (free) to burn the ISO file to a CD.file:///D:/COMPUTER%20INFORMATION/SYSTEM%20-%20INFO%20&%20TEST%20APPS/!%20%20%20Hitachi%20Drive%20Fitness%20Test%20(DFT)/Hitachi%20DFT%20Download.url
Since you have already made sure that the BIOS is set to try to boot from the optical drive before the hard drive all you need to do now is load the CD and restart your PC. The program will start running automatically.The memory (RAM) may be faulty.
Download, burn and run Memtest86+. It's also available as an ISO file to be burned to a CD. Allow it to run for at least 3 complete passes. No errors should be identified.http://www.memtest.org/#downisoThe power supply may be marginal or bad.
Your BIOS may have a tab called something like "PC Health". If it does it will show you the power supply outputs and the CPU temperature. The temp should not be above 50C. The supply outputs should be within this range:
+3.3: 3.135V to 3.465v
+5: 4.75V to 5.25V
+12: 11.4V to 12.6V
If any of these voltages are at or outside these limits then replace the power supply.