If it's a 15" mid-2010, then you may be having the following problem...
If you're having frequent kernel panics with your 15" mid-2010, or intermittent screen problems, the problem is, more than likely, the faulty NVIDIA GPU found in a number of those machines.
Here's just a sample of a kernel panic log that points to the faulty NVIDIA card:
Kernel Extensions in backtrace (with dependencies): com.apple.GeForce(6.4.0)@0x82ac4000->0x82b7afff dependency: com.apple.NVDAResman(6.4.0)@0x834a0000 dependency: com.apple.iokit.IONDRVSupport(2.2.1)@0x82fd3000 dependency: com.apple.iokit.IOPCIFamily(2.6.5)@0x7a802000 dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0x8301b000 com.apple.nvidia.nv50hal(6.4.0)@0x83c05000->0x84019fff dependency: com.apple.NVDAResman(6.4.0)@0x834a0000 com.apple.NVDAResman(6.4.0)@0x834a0000->0x8378dfff dependency: com.apple.iokit.IOPCIFamily(2.6.5)@0x7a802000 dependency: com.apple.iokit.IONDRVSupport(2.2.1)@0x82fd3000 dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0x8301b000
Here's the "official" Apple take on the issue - but the very real kernel panics need not be preceded by 'Intermittent black screen or loss of video'... in fact, you might not experience any video problems at all. Although video problems can certainly be a portent of things to come…
So what can you do? Print out a copy of your kernel panic and a copy of the Knowledge Base article and take them, along with your machine, to your local Apple Store or an Apple Authorized Service Provider. The unfortunate thing is that many people have passed the “three years from date of purchase” now and Apple is not honoring the free logic board replacement for many users. Some dealers seem to be making some exceptions for those past the three year mark, but don’t count on it…
Good luck,
Clinton