There's obviously a problem with the room temperature, or the placement of the case. Many cases have air intake vents underneath the case. If the case is placed on carpeting or other soft surface, air flow can be cut off to the interior of the case, causing overheating.
I built a somewhat high end machine for my brother-in-law gigabyte M/B GA-965P-DQ6, 2 GB Corsair Memory, Sapphire Radeon X1800GTO PCIe x16, SATA II 400 GB drive and SATA II DVD every format, 550W Seasonic S12 PSU. I used the packaged Intel CPU fan on a Dual Core 2 E6600 CPU. No over clocking.
Problem: at his place he reports a temperature alarm on the CPU at over 60 degrees C. He doesn't use it for gaming and sometimes it's just idling. I bring it back to my place and run it with a CPU and I/O intensive PERL script simultaneously with a McAfee virus scan and Firefox surfing. I get maybe 42 degrees C. It idles at 36 degrees. I've never seen anything like this. It's been running 24 x 4 days so far and nothing unusual. Thoughts?