How can i stop norton download manager from running

Tried installing 360 2014 for v3 pcs, on an XP system. Downloading was interrupted

by comcast problems and after 12 hours, is still running, It locked  everything and

after multiple reboots all I get is an error warning and freeze.

I tried installing Norton AntiVirus but an alert says Download is still running and to wait.

I'd like to have some virus protection while online but can't download anything.