XP startup prob: blue screen, reboot, repeat

Hello,

I am new here, and I'm desperate for some help with my Windows XP Pro machine. (I think I'm running SP2, but I can't be 100% sure; it's been a long time since I used this machine.) Apologies in advance for this post's length; I really am not sure what to do here and have tried some things already, and would really appreciate any help you can give me.

I have not used this computer for the past couple of years, and the few times I've tried to turn it on recently, I get a blue screen that reads:

STOP: c0000221 {Bad Image Checksum}
The image ole32.dll is possibly corrupt. The header checksum does not match the computed checksum.

The way it happens is that after the Windows XP logo screen shows up (the one with the "loading" bar), I get a blue screen that flashes so quickly I can't read it, and then the computer restarts. I can get the blue screen to stay by hitting F8 repeatedly as the computer boots up, then selecting "Disable automatic restart on system failure" from the menu.

Also from that F8 screen, I have tried starting in the following modes but the same problem happens, where it gets to the XP logo/loading screen, then has the blue screen flash and reboots:
- safe mode
- last known good configuration
- debugging mode

I have been pointed to this page (https://support.microsoft.com/en-us/?Product=winxp but I am a little confused by it, especially because I don't have a Windows 98 or ME disk. (This computer came from Dell in 2000 with Windows 98 on it, and I installed XP on it a year or two later from a Windows XP Professional CD, and used the computer successfully for the next few years, installing a service pack or two along the way. I can't find a way to follow their instructions to create a Windows 98 start-up disk from MS-DOS because I am not running 98 on this machine.)

Other message boards have suggested to try going into "repair" mode by inserting my Windows XP installation disk. I followed the instructions here (http://www.michaelstevenstech.com/XPrepairinstall.htm without backing up my data because I can't get into my operating system to do that. (I realize that is risky; didn't think I really had a choice.) I got as far as step 3, as listed under "XP Repair Install." But when I hit "enter" to start the Windows Setup, I got this message:

"Setup did not find any hard disk drives installed in your computer.

"Make sure any hard disk drives are powered on and properly connected to your computer, and that any disk-related hardware configuration is correct. This may involve running a manufacturer-supplied diagnostic or setup program.

"Setup cannot continue. To quit Setup, press F3."

Now, the computer came with a 20GB harddrive in 2000. At the beginning of 2005, a friend installed a new harddrive for me, 250GB, which replaced the 20GB. (The 20GB is no longer in there.) The 250GB drive shows up in the list of drives on the black-with-white text BIOS screen that shows up at the beginning of each reboot, so something must be detecting the drive.

So I don't know what to do now! Is my only option get a new harddrive, install XP on it, then run my current hard drive as a slave in order to pull files off it?