According to bleepingcomputer.com, popuper is a Trojan that is started at each bootup by a registry entry
Most anti-adware/anti-spyware programs have the ability to delete as well as to quarantine files. I have never used Pest Patrol so I don?t know about it, but you should check for that option. However, if the registry entry is not removed also, you may then get a registry error each time you boot.
If Pest Patrol does not completely remove this pest, try Ad-Aware, Spybot Search & Destroy, and/or Microsoft Antispyware. These all have free versions that can be downloaded. Actually, you should always have two or three such programs available because none of them catch all malware.
If you try to remove it manually, search not only for popuper, as Lil Abner suggested, but also for notepad2.exe which it often masquerades under (do not remove notepad.exe by mistake!). Check the above link to see which registry entries it may be using to load into memory. Your profile does not indicate anything about your level of expertise; if you are not familiar with registry modification, please ask for more help ? mistakes here can have serious consequences.
Hope this helps