Ben you have two problems (for other members that is called a "hanging curveball"
:
Problem #1 - It sounds like one of the cables in the computer is rubbing against one of the fans causing the noise. Not a problem to fix.
Problem #2 - You probably have some malware on your computer that is causing the instability. It needs to be removed before system stability can be restored. This can be a bigger issue.
Problem #1:
1 - Find a clear table to lay the computer.
2 - Take a digital picture of the back of the computer (to "remember" where everything should be plugged in).
3- Remove the connections from the back of the computer.
4 - Open the computer case (you might need a screwdriver). (Yeah, you will probably see lots of dust.)
Look into the case. Are there any wires touching any of the fans? Remember that computers are susceptible to static electricity. So, you need to always have one hand touching a metal part of the case when you are using the other hand to fiddle with the internals ("fiddle" is a computer term -
5 - You should see the wire that is rubbing against the fan which is causing the noise. Move it out of the way. That should fix that problem.
6 - Replace the cover and reconnect the disconnected connections using your digital photos(s) as a guide.
Problem #2:
Okay. This one can take some time and patience. Take a deep breath, stay calm, recite these phrases "I will not hit my computer", "My computer is my friend", "I like my computer". Keep a good kharma.
The following steps will be generic because I don't know your OS (which version of Windows), or applications installed.
1 - You need a get a copy of a decent A/V software and a decent spyware remover. If money is tight, download a free 30-day trial of something. Make sure to get both A/V and spyware scanners/cleaners. McAfee has 30-day trials:
http://us.mcafee.com/root/downloads.asp?id=freeTrials
2 - Start you computer and boot into "Safe Mode with networking" (the success of this connection depends upon how you connect to the Inernet). You should see the option to press "F8" when you computer first begins to start (and before Windows starts up).
3 - Log in to your computer and go into the control panel. You want to see what "applications" are installed. Some malware can be removed from Add/Remove Programs. This is one place where it can be tricky. If you don't know much about the software installed on your computer you might not know what you can safely remove. Send me a list of the items in Add/Remove programs and I will tell you of those I believe can be safely removed. You do need to remove the version of AVG since it isn't helping you remove your malware. Remove the AVG.
4 - After removing the AVG (and any malware you might find in Add/Remove Programs), install the 30-day trial. You won't be able to update it's virus definitions unless you have a connection to the Internet (that is why I suggested "Safe Mode with Networking" instead of just "Safe Mode". Update you defintions.
5 - You system might require a reboot. If it does, then reboot into "Safe Mode".
6 - Check the configuration of your A/V product. Make sure that it scans all files including compressed files. Scan you entire hard disk (all partitions). This will take a while.
7 - If you are brave (and depending upon which version of Windows you are using) you can also look at the "Run" lines in the system registry. There are utilities that make this easier, or you can run the "regedit" command to do it. You probably need some help to use this command. You can definitely hose your computer if you delete something that you should not have deleted.
8 - Anyway, if the A/V product finds and deletes the malware, you could restart the computer and see how it runs. You might need to repeat this process.
OR, (big OR) if your computer is really foobar, then a wipe and load clean installation may be required. This would require that you save all important files to a backup device (you know, those pictures of RSD in a bikini
, collect all of you software application CD's (you will need to reload all of your applications), make notes on all of your important system configurations (email settings, network connection settings, application settings, etc.) , get your operating system CD, boot the OS CD and reinstall the OS (have it reformat the partition during setup). Obviously, this is a more drastic operation that requires a higher level of computer skill to not mess it up.
Well, good luck. I hope this helped.
Of course, if your computer is down you can't even read this post. Kinda funny when you think about it.