Yesterday I noticed that there was this strong smell of smoke that smelled like someone had just burnt out a match, coming from my computer. I looked all around the cords underneath and did not see any smoke so I did not think that much of it. Later on, the smoke smell got worse, (it seemed to be strongest around the monitor area).. so I turned off the computer and unplugged everything and let it cool off overnight because I figured it must have just been over heated. I was off for a good 12 hours or so and so I turned it back on today and did not smell the smoke anymore until about a half hour ago. The same burnt match smell is here again and I cannot figure out where it is coming from except that it seems to be the strongest around the monitor area. Anyone know what I should do? I really cannot afford a new computer and am worried something might be wrong inside the cpu or something.. I am really bad with computers and only have a general knowledge about technical issues with them but I was told by someone that I might have to open up the tower and clean the fan or something? How exactly do I do that? Also anyone have any idea (ball park figure) around how much it would cost to fix if it continues? I have no idea what it smelling like smoke would mean except that maybe I need a new fan? Are those expensive? Should I also be using one of those air can things?

Any tips or advice would greatly be appreciated! Thanks!