My laptop is making high pitched screeching noises
Normally I am very good with computers, but my laptop has been giving me so many problems. It is a Dell Inspiron 6400, barely a year old and I already had to replace the hard drive, because when Dell built it they put in a faulty piece. Well, I just got my laptop back a month ago, we down graded it from Windows Vista to Windows XP. Yet, since I got my laptop back it has been occasionally letting off a high pitched screeching that last for a second. And the other night it somehow installed NetWare and changed start window to classic view. Happily I got that problem fixed and deleted the NetWare, but now the screeching sound got a louder and lasted longer then normally.
My brother suggested it to be a Trojan virus but as he explained, a trojan takes place and works when your computer is shut off, but these problems have been occuring while I am logged on. Somebody also suggested it might be spyware but I have cleaned all of that out, defragmented my laptop, and even did disk cleanup. I do virus scans and spyware scans every other night; nothing has been reported to be wrong. I have three different security systems running at all times.
Sorry about all my rambling, but felt like pointing out all the details before asking you all for you opinions on what is causing the screeching. So, please people if you have any idea of what is wrong with my laptop and how I could fix it give me some feedback.