Question : XP device manager error: Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)

I started getting this error message two days ago for my Realtek 8139 LAN NIC card that is integrated to the motherboard and I can no longer access the network. I've been unable to fix this and would appreciate suggestions.

Here's what I've already tried that did not work:

1.      Update driver to latest version from Realtek’s web site.
2.      Uninstall/reinstall device (tried this with an with a reboot between the uninstall and reinstall).
3.      Uninstall any Windows updates installed near the time this happened and reboot.
4.      System restore (no restore points exist far enough back to be before this started)
5.      Removing the upperfilter and lowerfilter registry keys (didn't have those keys to remove)
6.      Install a different network card (I added a USB WLAN adapter to the already-installed integrated LAN NIC in the motherboard). That adapter doesn’t work either and gave me the same code error in the device manager. This indicates that the issue is not localized to the Realtek NIC.
7.             Full system restore from backup (I do not have a full backup of the system so I can't do that)

Answer : XP device manager error: Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)

I tried all of these options and none of them worked.  I ended up doing a windows repair install and that resolved it.

Thanks to all for your suggestions, though.  They were good, unfortunately they just didn't work.