your symptoms sound EXACTLY to the letter like the problem that my 24" iMac 2.33GHz Core2Duo machine exhibited. severity of the problem was definitely related to heat and CPU/Gfx load. since it was still under warranty, Apple tracked it down to the graphic card problem, though they also replaced the CPU fan and logic board while they were at it. I know that doesn't help you specifically, but just FYI
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your symptoms sound EXACTLY to the letter like the problem that my 24" iMac 2.33GHz Core2Duo machine exhibited. severity of the problem was definitely related to heat and CPU/Gfx load. since it was still under warranty, Apple tracked it down to the graphic card, though they also replaced the CPU fan and logic board while they were at it. I know that doesn't help you specifically, but just FYI
as for what you can do in your case, since it's heat related, it's probably worth a try to follow the thermal paste suggestion above.
another thing - perhaps check if your fans are working correctly. install something like iStat Pro where you can monitor your MBP's internal temperatures and fan RPM speed. perhaps it's something as simple as a faulty fan? that's worth a check too
your symptoms sound EXACTLY to the letter like the problem that my 24" iMac 2.33GHz Core2Duo machine exhibited. severity of the problem was definitely related to heat and CPU/Gfx load. since it was still under warranty, Apple tracked it down to the graphic card problem, though they also replaced the CPU fan and logic board while they were at it. I know that doesn't help you specifically, but just FYI
as for what you can do in your case, since it's heat related, it's probably worth a try to follow the thermal paste suggestion above.
another thing - perhaps check if your fans are working correctly. install something like iStat Pro where you can monitor your MBP's internal temperatures and fan RPM speed. perhaps it's something as simple as a faulty fan? that's worth a check too