Have you upgraded to Mac OS 10.7 Lion? My father recently upgraded and immediately experienced hardware issues with his 2008 Macbook Pro (with NVIDIA graphics card). His particular model was known to have a graphic card defect and was a part of a recall that NVIDIA conducted. Fortunately, Apple replaced the motherboard and all is well now. This triggered some searches of my own, which led me to this Ars technica post and Apple Discussion thread. I am working with a 2010 Macbook Pro so I am holding off on the upgrade for now.
In preparation, I’ve downloaded Carbon Copy Cloner and successfully created a backup to an external USB drive. The CCC tool is very easy and intuitive to use. I highly recommend it. I also created a USB thumb drive installer for a clean install of Lion from a simple to follow Mashable post. I may pull the trigger on the upgrade soon and hope for the best. I’ll let you know the results.