Mapped drives in Windows XP Disconnect Overnight

Does his PC go into sleep mode or does the hard drive shut down?  

No the power settings are not set to touch the pc. I did just notice the checkbox for "Allow the pc to shut down this Device to save power" was checked the the NIC. I changed this setting to see if it will resolve the problem.

It could also be:
 
 
Mapped Drive Connection to Network Share May Be Lost

I read this article. The symptoms are diffrent from what I experience. The mapped drives do not reconnect when you attempt to access them. The fix alters settings on the server. Since no other users on the domain experience this problem, I'd rather not impliment this fix.

Create a batch file for the user to execute every morning that renews his DHCP lease.  If that doesn't do it, then add to the batch file so it then deletes the networked drives and reconnects them.  


-----example-------
cls
ipconfig /renew
exit
-----end-------
-----example-----
cls
ipconfig /renew
net use /delete (drive):
---repeat delete line for each mapped drive---
net use (drive): \\server\shared path
---repeat for each mapped drive---
exit
------end-------

Sometimes the old ways are the simplest.

Here is an update of the symptoms.
The pc has been locked for 2 days and the mapped drives are gone. Checking 'Net Use' shows no entries are in the list. I cannot remotely navigate to \\computername\c$. From the pc i cannot navigate to \\domain controller to see it's shares, but i can navigate to \\domain controller\sysvol. The symptoms are the same for \\fileserver\user's folder. Using Windows Explorer to browse the network shows the domain as empty. I can navigate to shares on the servers as above and the shares will find thier way into Windows Exlporer.
The only error in event viewer is: "Application popup: svchost.exe - Application Error : The instruction at "0x50112252" referenced memory at "0x005d0df4". The memory could not be "written"." After this message all the services error and stop. The services include DHCP Client, Server service, Workstation service, Computer Browser, Disk Manager. When the error appears the associated .dll file is wuaueng.dll. This file appears in the i386 and software distribution folders. I assume it's a part of the Automatic Updates.
The error was recreated when attempting to use windows update on the pc. Cleared the Software distribution folder and Windows Updates it working. I registered the Windows Update .dll files and ran a sfc /scannow. Installed all avaliable updates.
Adjusted the autodisconect in the registry to ffffff.

Just checked the running services and after selecting services in computer managment the right pane is empty. I can click on "Standard" at the bottom and that pane works, but "Extended" is empty. All the services that stopped above are still stopped. Started Windows time, DHCP client, and Computer Browser services. I can now browse to \\fileserver and see the shares,
The problem is that these services are stopping and are not starting again. There are alot of services in the list that are not started. Its not hard to believe why the mapped drives were missing.
Here is the error that appeared just before all the services crashed:
Application popup: svchost.exe - Application Error : The instruction at "0x50112252" referenced memory at "0x005d0df4". The memory could not be "written".

When I say "just before" I mean 18 hours before.

Every time I've seen the behavior you've described, the machine has been infested with malware, or has been cleaned of malware, but the damage was already done.  In every instance, it's taken a new install of Windows.

The repair completed and the error did not return after the first login. I'll leave it locked for awhile to see if it reoccures.

If the repair works, then it wasn't malware, but corrupted files and/or registry.  Hope it works.