Revenge of "Windows Installer could not be accessed"

[Mantrid]

Whenever I try to install a program, my computer (Windows XP SP2) says that the Windows Installer Service can't be accessed.

I had this problem before, and after doing everything the internet suggested, I eventually got fed up and did a reinstall of Windows.

Now, after I reinstalled, everything worked fine. I could install things no problem. And then I decided I wanted to try and move over my old "Documents and Settings" folder since I wanted to retain all my music and photos and so forth.

Well, I booted into a disk of NTFS4DOS, and renamed the folders. After I did this, the computer booted with all of my old settings, and My Documents folder was as it was before the reinstall, but some programs (like Opera) were broken. I changed the folder names back. So I was sort of back to where I was after the clean install. After this, I booted into Ubuntu, and copied the contents of the My Documents folder to an external drive, booted into Windows, copied the files over, and then the problem started up again.

I did everything outlined on Microsoft's site, like I did before, I verified the files are in the right place.

I'm not sure what else to do. I want to retain my old files, and I don't want to reinstall Windows again. I speculate that it has to be a virus or something because simply moving the files around shouldn't have affected the system files, or the registry. But I've scanned with Avast!, including a boot-time scan, and that turned up nothing. I'm going to run a chkdsk tonight, and see if that fixes anything (since before the reinstall I resized the main partition with PartitionMagic 8, and I think that might have affected some other files, since I have some mp3s that won't play now).

Ideas?

[dub-u]

It sounds to me like your NTUSER.dat file is the culprit. Try creating a new account and copying this file from the new account to the account you are trying save. It is hidden in the My Documents folder.