Error Loading Explorer.exe.

[Muddy]

[Gecko]

Can you boot into safe mode Command prompt only?
Reboot in to Safe mode:
Restart Windows after you see the BIOS screen and before Windows starts to load.
Start tapping the F8 key. The Windows Advanced Options Menu appears.
Use the Arrow key to ensure that the Command prompt only option is selected.
Press Enter. The computer then begins to start in Command prompt only.

If you can then and the command prompt type:
Scanreg /restore

You will get a screen where you can select which registry backup to use.
Keep trying each of the five backups until the system boots.

If you cannot boot into safe mode then the only chance of fixing it would be to use a win98 boot disk.

Boot the system from the boot disk at the command prompt type:
chkdsk c: /F

[Muddy]