I am having a dell XPS(L501X) laptop. It had mcafee antivirus solution(licensed version) installed in it from the beginning. but since it expired so i uninstalled it and installed microsoft security essentials recently but it was not initialized correctly and was giving some error which according to google answers was due to remnants of mcafee left in it. i then deleted all the folders and registry entries of mcafee but nothing happened and one of the registry entries' were unable to delete. my microsoft security essentials was detecting a trojan necurs64 and was not being able to remove it. it was repeteadly asking me to restart my system and when i did so my windows started attempting repairs. so i uninstalled the same. now i m not having any antivirus. What can i do now and how can i restore my system to some past date because its not showing a restore point. I am having windows 7 premium.