I was on my in-law's PC that trying to merge a partion with Partition Magic (Merging with main C drive). During the merge process, I got an error. It told me to hit any key to exit and reboot. After doing so & trying to load back into Windows, I got an error that it couldn't find a file and that I should insert the setup disk and run the repair utility. I did so, but it just takes me to the C:/Windows prompt. What do I do next to try and repiar my installation of Windows XP?

did it by chance refer to anything called an mbr aka a master boot record?

OK, I found out the exact name of the file missing. Here is what it said it can't find:

"system32/DRIVERS/PCI.sys"

Will the repair utility fix this file? Also, the PC doesn't have a floppy drive so I can't use rescue disks that can be made by Partition Magic

When you put in the XP CD and it boots off the cd, the XP setup files copy across, and at the 1st screen, you should be able to choose Repair. Press r, and this will start the Recovery Console.

When you are in the recovery console, choose your Windows installation (You will see what I mean when you follow the instructions.)

When you are sitting at the command line(C:\>Windows), access your CDROM drive by typing the letter followed by a colon, eg "D:". It may also be E:, F:, or G:.

When you have changed to the CDROM drive, type the following:

cd\ <enter>
cd\i386 <enter>
expand pci.sy_ C:\pci.sys <enter>
C: <enter>
cd\ <enter>
copy pci.sys C:\windows\system32\drivers <enter>
If it asks to replace, confirm.

Then restart your computer. If it finds more files missing, you may need to replace them using the same procedure.

Once I get to my CD drive and type "cd\", it gives me the following error:

"Command is not recognized. Type help for a list of supported commands"

I also tried changing to other available drives (D: & E thinking maybe they are the CD-Rom's drive letter, but still got the same error,

Try adding a space between CD and the path. If that does not work try the command chdir instead of just cd (it is the longhand form). I suspect it is just the space you are missing... Assuming that is the only issue the commands should be:
cd \ <enter>
cd \i386 <enter>
expand pci.sy_ C:\pci.sys <enter>
C: <enter>
cd \ <enter>
copy pci.sys C:\windows\system32\drivers <enter>

Hope this helped...

Hell yeah, thanks for he advice, the xp disc worked, in repair. I was holding my breath because it was lookin' like it wiped my harddrive at first saying "Welcome to Windows" I about fainted! Lol

Anyways, thanks greatly!

can you do this with a floppy disk
cause my windows XP professional just crashed
missing pci.sys
i tried boot floppy discs