Something nasty appears to have made it's way on to my PC & is turning off my firewall & antivirus protection.    I have tried reinstalling Norton A/V & I get messages that there is not enough space and it should be deinstalled. Nothing will run correctly.    What do I need to do reformat & reinstall everything?  I have even tried online scans but get no results as Active X will not download.

 

I'm a bit clueless.  Help?