Does this problem go away, at least temporarily, when you reboot the computer?
On the side of your computer, you should be able to remove the side panel to the case. If you do this, can you try, without touching anything inside, to determine roughly what part is making the creaking noise?
Reboot your computer and press F8 every 1 second until you get an Advanced boot menu. In there, select Safe Mode and let it boot up. When you login there, does it give you your normal desktop? (Note that things will look really big and your icons will be all jumbled around, but you should be able to see your desktop. Also, you won't have Internet access or anything like that.)
On the sound, did you open the case and try to see where the noise was coming from? Most likely, it is coming from one of your fans. When it makes the noise, you should be able to lightly press on the center of the fan (Not the part with the blades) and the noise will go away when you press on the fan that has the problem. There are fans that are mounted on the case and there is probably another one that is mounted on the main board and sticks out from there.
Sr. Network Engineer
A+, MCP, MCSE, 15 years of experience
No problem on the miscommunication. The F8 option is something that is built into Windows and wouldn't be affected by a virus or anything else so it has to be there unless something really deep is messed up.
What brand keyboard do you have? Is there a Fn lock key on it? If so, try pressing that once you boot your computer, then press the F8 key. (The Fn lock key changes the function of the F keys.) Also, are you pressing the f and 8 keys or are you pressing the F8 key above the numbers?
Below is a link to a picture of a keyboard. Please confirm that the key you are pressing is the F8 key just below the U in the UNOTRON label.
The link is http://www.unotron.com/US/images/keyboard_plan2.jpg.
I am sorry to harp on this issue, but we really need to be able to get into Safe Mode to be able to take the next steps.