Downloaded clamwin & now my PC keeps shutting down & starting up. The log in appears on windows; I log in, sreen appears with all icons, including clamwin & then immediately restarts again. This keeps happening, even after manually shutting down, replugging PC back in & then the same cycle begins again. The screen doesn't stay on long enough to open programs so that I can uninstall. Now I cannot use my computer at all. What can I do? Help please!

Clamwin does not install any system components, such as drivers. Therefore it cannot cause the problem you described. Try booting into Safe mode and looking at event logs.