Blue Screen.

I ve brought a new laptop, hp-dv6-3053.
it had pre-installed 3gb ddr3 ram, and i upgraded it to 6gb ddr3(2gb+4gb).
but after installing new ram, i started to have problems of blue-screen where it says, dumping physical memory.
It has been going on, and frequency varries from 1time a day to 4 times a day, especially when m playing nfs carbon or solidworks.
I tried to remove ram and insert again, or change the number of cores in msconfig, but no avail and continues.
Help?
OS:Windows 7 Home Premium x64;
RAM:6gb ddr3;

yup i tested! it passed 7 passes without any errors.
well, i changed my processer into 2 cores, i.e. i increased num of processor used in msconfig. after that crashed only once. since it is yet to be crashed till now, iz it coz of processor or some other problem?