WinPro is malware ... but I'm sure you have guessed that already. I should add that it can partly install itself using a 'drive-by browser hijack' unless you have sufficient protection ... and Norton isn't sufficient protection, unfortunately.

It's a little tricky to get rid of since it tries to remain in your system by throwing in hooks to keep itself on your computer.

Grab yourself a cup of coffee and brace yourself for a bit of a slog to get rid of it.

Here are the removal instructions on Spybot Search and Destroy forums:
http://forums.spybot.info/showthread.php?t=6021

You should begin by reading this thread, however:
http://forums.spybot.info/showthread.php?t=4015

You will see references to a program called HijackThis, and lots of references to HijackThis logs. That program is available from here:
http://www.spywareinfo.com/~merijn/programs.php

HijackThis logs look like this, except longer, so don't worry when you see a whole load of seemingly complicated 'code' that looks like this when you are reading the threads on the forums:
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn0\yt.dll
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {192c5b4a-3efd-40c7-9f99-c472deb8efc0} - C:\Program Files\Perfect Codec\isaddon.dll

It may not be a bad idea to sign up to Spybot forums before you do anything and to seek assistance should you encounter any difficulties when going through the steps in the threads above:
http://forums.spybot.info/index.php