If you know someone with a UPS and you could borrow it, there is a good chance that is your problem. There are some higher end power bars that will regulate the current to keep it nice and even.
Monster Cable is a brand I highly recommend. They also make voltage regulators and UPS units as well so you should be able to find a power sollution that is in your budget.
If you can borrow a UPS for a test and find it doesn't help I would pursue getting warranty coverage. If it is a heat issue, and you are not over clocking, then it could be from a faulty fan or even from a bad component on your MoBo (mother board) that is creating excessive heat. I would also recommend getting some one to look at it with your warranty coverage before you try anything that might void any warranty you have.
In my experience problems like these are not always easy to diagnose, not even in a workshop. If you do take it in for warranty work it is likely they'll just replace parts rather then spend too many man hours trying to fix it.
Hope that helps.