Search your System drive [Normally C ] for .scr files.
You will find your screensaver , delete it.

For any query, search          > www.Google.com
Want to know about a term  > http://en.wikipedia.org

Without knowing how it's "messing up" your computer it's hard to be
specific. However, many "free" screensavers downloaded from the web come
loaded with malware. That may be your problem.

---
Ted Zieglar
"Backup is a computer user's best friend."

Did you try uninstalling it either from Add/Remove Programs or through an
uninstall utility that is under Start -> Programs -> (name of screensaver)?

If you did and it didn't work then try going to Start -> Search. Choose All
Files and Folders. Under file name enter *.scr and hit enter. Find the one
that has the same name as the one you are trying to uninstall. Delete this
file.

-Dan

Christina,

Give us some details. Name of the screensaver, where you downloaded it from, how is it "messing up" your system.

Details are important because most of these malicious programs are known and documented. There will be specific removal instructions.

Check the following registry key (logged in as user having problem):

HKEY_CURRENT_USER\Control Panel\Desktop

In right panel, look for SCRNSAVE.EXE.  The pathname of the screensaver is
the data associated with that value.