Load needed DLLs for Kernel

I have a Windows XP running PC with two DIMMs 256MB RAM each. Some days ago I removed one of the DIMM to use in other PC after that I tryed to put it back, but when I start up the PC, after POST, show the following message once:
“Windows could not start because file is missing or corrupt: C:\Winnt\System32\Drivers\Pci.sys”
I shut down the PC and wait about a minut, after that boot again and after POST received the following message: “Windows could not start because of an error in the software. Please report this problem as: load needed DLLs for Kernel” I shut down again and removed the DIMM and the PC boot OK. Think the DIMM is damage and tryed in another PC and works fine. Can not understand what is happen here! Any help?