Could my other computer have a virus?

Well, last night I turned on my other computer loaded fully in the task bar Antivirus was disabled with windows security alerts alerting me to it (This has not happened in a long time I never downloaded things recently...) Then a strange popup pops up and says windows needs to shut down and blah then the window disapears, then another window comes with a countdown then another comes saying "Windows is logging off" then the computer shut down....Which I don't understand I don't do bad things on my computer...Don't have Limewire I don't know if this is a virus or what...Please answer as soon as possible, thanks.