PC Advice?

Throwing this out there, in the hopes that somebody has an easy step-by-step solution they can offer:

Dotta Numba 2 runs a PC with Windows XP. Apparently, somewhere along the line, she got something nasty onboard — but doesn’t know what or when.

Now, when she starts up, she gets the desktop wallpaper — no applications or icons, and the following error message:

“Data Execution Prevention-
Microsoft Windows

To help protect your computer, Windows has closed this program.

Name: Userinit Logon Application

Publisher: Microsoft Corp

— Close message”

When you click “close message”, you get:

“Userinit Logon Application has encountered a problem and needs to close.”

Any ideas?

Oh, and here’s the fun part: She doesn’t have the system restore discs.

As a Mac user, I’m pretty much useless here.