winXP error message installing new software

[wesbark]

I am running XP on a Toshiba 1805-s207 laptop and trying to load new software but getting an error 1931 which is telling me "The windows installer service cannot update the system file C:\Windows\System32\mfc42.dll because the file is protected by windows. You may need to update your operating system for this program to work correctly." I have all the updates installed. I didn't have this message on softwares I have loaded before. Now it is showing up routinely. Any help?

[Grendel]

You probably have some spywear on your computer called Xupiter; it corrupts the mfc42.dll file.

Go to their website and run their uninstaller.

[wesbark]

Grendel, thank you for your response. I have attempted
to find Xupiter in the registry and program folders and there is
no evidence of it anywhere. I haven't had any trouble with my
opening page in ms internet explorer.

Do you have any other thoughts?

Does anyone who might be following through this thread?

The problem is that windows is "protecting" mfc42.dll file. An error
message screen comes up when I am attempting to load a new
software CD on my laptop running XP. "Error 1931. The windows installer service cannot update the system file C:\Windows\System32\mfc42.dll because the file is protected by Windows. You may need to update your operating system for this program to work correctly."