My pc is unstable. every minute the pc stops responding mouse doesnt move programs stop responding and then after 30 secs it comes back to life. did a nav scan and it found a trojan couldnt delete or fix it but put it into the quarintine. then the problems for a while stayed away, then it came back pc stops responding and a new thing is that my dvd drive is dissapearing. i dont get this cause now when i do a nav scan it doesnt find anything. so is the trojan still on my pc, messing with it. also have problems with booting. sometimes its does it perfect, sometimes it takes 4 times to get to the desktop i hope you can help me with this, cause i have now idea how to fix this and i dont want to do the format if there is another way out.