CPU usage issues

Hi, I have an HP g72 notebook with 4gb of ram and an intel core i3 processor. My computer has been running fine but very recently it has been very freezy when i do simple things such as internet browse or play flash games. The fan made a clicking noise the other day and some smoke had been coming out. I turned the computer off to prevent damage. Could it be a cooling problem?? The fan still runs fine with no issues. But if i leave the computer standing for a few hours, the CPU usage climbs to 100 percent with nothing open at all. I already scanned with avg and found nothing, and no viruses had ever really gotten on this computer. I have no idea whether its the fan or something else.
 
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