Vista - very high processor temps

hey
my processor is a core 2 duo E4600 @ 2.4Ghz.The problem is that sometimes when i switch my pc on the beeping overheat sound comes and my pc turns off. sometimes when i do manage to turn it on, i use coretemp and speedfan for the temp. reading and in the beginning it reads at 83 degrees celcius! then it cools down and the temp. remains betwwen 65c - 70c. yesterday the nomal temp was between 40c-45c. the sudden increase in its normal temp scared me. this increase happenned after i cleaned and dusted the insides of my pc. while dusting it i didnt do anything near the processor. i have 3 8mm fans in the pc. 1 blowing on the processor and 2 sucking air out-one from the back and one at the side.
So can any1 help me out here? should i get a new set of fans or buy a new processor?
any help would really be appreciated.

ps. i use coretemp and speedfan for the temps.

Check and make sure the fan is spinning.

Make sure the fan ON the CPU is spinning. Also make sure the clips or whatever you have that holds the CPU's cooler on. didn't come loose.. anything over 70c at ALL.. is dangerous.. I'd turn off at those temps. you might need to get some thermal paste and re-seat the cooler for the CPU. has it always had these temps? if not then something is loose. or the fan is bad or something.

yep i checked it the fan is a bit loose(2 out of 4 clips broken), so should i get a new fan? or a new processor

Hi mahdir24,

A new heatsink/fan (HSF) assembly should be sufficient. Make sure that you get one that is compatible with your motherboard and suitable for your processor rating. Don't forget to check whether you need one with 3 or 4 leads to the fan, and get the appropriate one.
Carefully remove the old HSF and clean the top of your processor to remove all traces of the previous thermal interface material (TIM). If your new HSF has a pre-applied pad of TIM, skip the next part.
Next, you need to apply fresh TIM to the top of your processor. Apply a VERY SMALL amount of TIM to the centre of your processor and, using either a plastic card such as a credit card or preferably your finger (use a latex glove to protect your fingers and to prevent contamination of the TIM), carefully spread the TIM over the surface of the processor so that it is covered in a very thin layer. DO NOT use too much.
You can now replace the HSF assembly. Carefully lower it down over the processor, taking care that the leads from the fan can reach the appropriate socket on the motherboard without over-stretching. Make sure that the mounting pins for the HSF are lined up with the holes in the motherboard and press them down so that they click into place. You will need to apply quite a bit of force here, and it is advisable that you do 2 pins at a time on a DIAGONAL pattern.
For detailed instructions, refer to the leaflet that comes with your new HSF - this might come complete with a tube of TIM and possibly a latex glove if it doesn't have a pre-applied pad of TIM.