Ok, try this to start off with:
1) uninstall Symantec and reboot if necessary
2) download & install the permanently-free AOL Kaspersky from
here. It's ok if you get a prompt saying the site is registered to someone else, it's registered to AOL. Skip the optional security toolbar when you see it offered during installation. This does NOT result in your system being swarmed with AOL junk, btw
3) after installing it, you have a green safe icon in your system tray. Right-click it and choose
Update and make sure it updates successfully, then reboot. At this point, you might already be getting virus detections, but don't get bogged down trying to deal with the alerts yet.
4) after rebooting, open the antivirus, then click
Settings at the top. Go through each page of settings from top to bottom and max them all out. Set everything to automatically delete stuff instead of asking.
5) now run a full scan by right-clicking the green safe and choosing Scan My Computer.
6) also run the free
F-Secure BlackLight rootkit detector and rename anything that BlackLight finds is being hidden.
What's the result, did it find anything malicious? If so, what exact names of stuff did it detect (for example,
Trojan-Downloader.Win32.Zlob.ayp or whatnot). You can find this info by opening up the antivirus window and click in the Computer Protection Status window, and go through the logs. Is the problem resolved, or do you still get popups?