Can't get into XP

Well, I changed my loading and log-on screens for XP. Got a couple from ThemeXP, booted up in safe mode, made my changes, and restarted, before shutting down, the logging off/ shut down screen looked fine, it was the one I changed to. Restarted, and the loading screen comes up fine. After it loads, my screen goes black, the monitor power light goes from green to amber, then the monitor gives me the No Signal message, and the computer restarts. Can't get into XP using Safe Mode either. Restoring the last known good configurations still doesn't let me in.

Anyone know what I can do? Boot from a floppy? Anyone know how to make an XP Boot Disk?

No need for a boot floppy.
Use the XP CD.
You can use the repair console (I never had success with this) or you can repair XP by doing the following:
Shut down your computer. Press the power switch to turn the system back on and directly after continuously press the delete (F1 or F10 depending on your system) key to get into the BIOS. Select “Advanced BIOS Features” (use arrow keys to highlight, press Enter). Change the boot order to boot to CDROM first and then to HDD-0 second.
Then press F10 to save and exit (put the XP CD in before you exit).
After the reboot, press any key to boot to CDROM, and the XP setup should start.
When prompted, press enter to install XP. It will find your previous install and give you several options. Pick the "Repair" option. The XP setup may reboot the computer several times. There is no need to press any key to boot to CD during this process. After it’s all done, you can reboot, get back in the BIOS and set the boot order back the way it was. I usually set the first boot device to HDD-0 and disable the rest.

Understand that you will loose any previous settings or tweaks you have done to XP.
You may also have to reinstall some programs and drivers.
If you use multiple hard drives, I also recommend pulling the power plug (disabling them) on all but your c: drive.
Good luck!

Err... it keeps prompting me to enter the administrator password, but there is no administrator password. What do I do?

XP or the BIOS?
If you have multiple users in XP, you will need the admin password.
Yours may work, if you are an administrator in XP.
Otherwise, you may be able to just hit “Enter” and the XP setup will continue.
If it’s in the BIOS, then you’re stuck.
You will need the password.
Last resort would be to format and reinstall XP if it doesn’t let you in.
Good luck!