Simple fix for missing or deleted Rundll32.exe file
Put the Windows XP CD ROM disk in the CD ROM drive.
Click Start, and then click Run.
Type: expand X:i386rundll32.ex_ c:windowssystem32rundll32.exe in the Open box, change X to the letter of your CD ROM Drive. Run it.
Restart the computer
if that fails try fix below:
Go to Start, then to Run, and type in “SFC.EXE /SCANNOW” (without the quotes – and with a space between the SFC.EXE and the /SCANNOW). The press Enter. (For VISTA, go to Start and type in the above information, then go to the top of the box and right click on SFC.EXE /SCANNOW and select “Run As Administrator“)
The program may (or it may not) ask you for your Windows XP installation CD – please insert it at the prompt. If it doesn’t ask you for the CD this means that it wasn’t necessary to replace any files.
File from SP2 i386 folder
File from system32 folder