freezing Dell inspiron n5110 notebook (4Gb RAM-i5)

I bought a Dell inspiron n5110 notebook (4Gb RAM-i5 processor)2 weeks ago, on 15 October 2011 

(it was a bad decision), the same day,it began freezing... Intel Turbo Boost Monitor rises to 2.90 Ghz, and freezes... 
I contacted the seller, they didn't care. 
I contacted DELL support, they accepted the problem and last week they changed the mainboard and the Hard Drive,

 but the notebook repeats freezing. it freezes 2-3 time in an hour for 1-5 minutes... 

The seller told me to use the FN + F2 combination to shut the bluetooth and the wireless connection,

 if I do it, the Turbo Boost monitor descreases from 2.90Ghz to "0 Ghz".. 
My question is, can anyone in this forum using a Dell help me to fix my problem? Any idea? 

Because today I called Dell again (its the 4. time), they told me that they can change the notebook with a new one 

but it takes between 4-6 weeks. It is a long time....
I need to use this notebook because of my writings. So if anyone knows why this happenes, and the solution, 

please contact me.
Thanksssssss.....