You should probably go to here http://uninstallers.blogspot.com/ and get the removal tool for mse to get rid of the left overs before you reinstall your av too, you can also find other uninstall tools there for any other av's you may of had in the past, once done removing please follow sded's advice.
I'll make it easy for him. Here is the MSE Uninstaller tool:
http://support.microsoft.com/kb/2435760/, then reboot your machine.
You may also want to run a cleaner in between uninstalls like
CCleaner, a freeware system optimization, privacy and cleaning tool. There is a
Slim version available as well at
http://www.piriform.com/ccleaner/builds – 4th option down. It removes unused files (cache, temporary Internet files, etc.) from your system, allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history.
Then you go on to the information posted by sded.
I use Avast and OA with XP and use the exclusions without any problems.
To exclude OA in Avast:
· Settings > Exclusions > Add > search for Online Armor and click on the box to the left of it and add it, then click OK.
· Real Time Shields > Expert Settings > Trusted Processes > Add > search for Online Armor and click on the box to the left of it and add it, then click OK.
· Behavior Shield > Expert Settings > Trusted Processes > Add > search for Online Armor and click on the box to the left of it and add it, then click OK. Also change action to take in Behavior Shield to “Ask.”
To exclude Avast in OA:
· Open the OA GUI > Options > Exclusions > Add > click on the pop-up window and find C:\Program Files\Avast Software\.
· When you reboot OA, after the Safety Wizard, OA goes into Learning Mode, make sure all Avast shields are left on and leave everything alone until it is done.
· Reboot your machine again; OA requires two boots. After this second reboot, you
may get a pop-up asking you if you trust Avast (if you didn't put the exclusions in already). Answer the pop-up as "Trust Always" and "Remember My Decision" and you should not get any more pop-ups. Answer incorrectly and you will get future pop-ups.
· Open the OA GUI > Programs > untick "Hide Trusted" so that you can see everything > look to make sure everything from Avast is not "blocked" (red) or "ask" (yellow). If it is, right-click the item and change it to "Trust." Reboot.
· Open the OA GUI > Options > Backup/Restore > Save your settings once you have everything the way you want it.
Let us know if you have any questions. Thank you.