What happens: Laptop screen goes off, any audio that may have been playing may jar for a second or two and then stops but the machine does stay on - keyboard remains lit and can hear the fans on as well. System does not recover, I have to do a hard shut down by keeping the power button pressed. The machine can be started immediately after this and can work for hours without the problem occurring again.

I have found no pattern to this problem, it has happened when I'm in my browser, working on code  or when playing a game. The frequency of the problem varies from happening upto 4 times in a single day to having no issues in almost a week. The problem happens most frequently when resuming from suspend - the system will recover, windows comes up and in the space of a few seconds, it hangs as described above. I have been facing these issues for a little over a month (occurred over 20 times); I reviewed software changes made during that period and there were no services or drivers or any other background processes installed at that time.

This is a 64bit system with Windows 7 SP1.

RAM: 16GB

HDD: 250GB SSD + 750GB SATA

Graphics: Nvidia 580M with 2GB VRAM

I have run the entire system diagnostic a few times with no issues being reported.
I do have the latest drivers installed, including the latest NVidia drivers.

I'm leaning towards this being a heating problem, which I reported over two years ago and have resolved by simply keeping the laptop elevated: http://en.community.dell.com/owners-club/alienware/f/3746/p/19444897/20102413.aspx#20102413

However, when my graphics card gets hot, I simply get graphic lag, it doesn't shut down the system (and this has happened a couple of times after I started experiencing the hanging problem). As far as CPU temp is concerned, I ran a stress test to see the temp go beyond 100 degrees for a few seconds but the machine stays functioning fine. Also, I assume if the CPU is too hot, the system will power off, which is not happening in my case.

My system is still under warranty, but I'm half sure Dell is going to tell me to reinstall the OS before doing anything, this is something which I have no time for and I'm convinced this is a hardware issue.

Any ideas on how to diagnose this problem further would be highly appreciated.

Thanks!

Brian.