Problems With Rundll in XP

History
The rundll32.exe is a Windows-based process that opens .DLL file's shared libraries into system memory, increasing the efficiency of your computer. In previous iterations of the Windows operating system, rundll32.exe was called rundll.exe. Hackers and malicious virus creators immediately took advantage of the change and created backdoor infections that installed rundll.exe on Windows XP systems. The infected version of the file was designed to install malicious viruses to attack system files.
Location
The proper location for rundll32.exe is in the C:\Windows\System32 folder. If it is installed in any other location, then it is not a system file and is more than likely a virus. In addition, since rundll.exe is not a Windows XP system file, then the inclusion of the file anywhere in the operating system is an indication of an installed virus.
Control Panel Error
One of the problems with the rundll32.exe process in Windows XP is an error that generates when a user attempts to open the Control Panel application. In some instances, an error message is received stating that Windows cannot find the C:\Windows\Rundll32.exe file. If this is the case, then it could be the result of a missing or damaged rundll32.exe file. The quickest fix for this error is to insert the Windows XP installation disk into the CD-ROM drive and copy the original rundll32.exe file.
Corruption or Deletion
A virus or unsafe program can often overwrite or uninstall the rundll32.exe file. If this is the case, Windows XP will slow down, and numerous applications will become unstable or nonfunctional. In order to restore the rundll32.exe file back to an accessible state, you will have to copy it from the Windows XP install disk, or find a safe source of the file on the Internet.
General Issues
Given that the rundll32.exe program is used with thousands of different programs, it is not uncommon to receive a multitude of errors from the rundll32.exe program. The most typical error is a program crash. If the rundll32.exe process stops running, the user will receive an error message. If an error continues after numerous attempts, then the best solution is to run a virus scan to determine if the rundll32.exe program is infected, or if the .DLL file that XP is trying to expand is actually a virus.