That usually indicates a failed overclock. If it still refuses to reboot, reset the CMOS and let it cool for a bit. Then go back in an try something lower.
I don't know if this will help, but we have a similar situation, this is my overclock.
MSI P35-Neo Motherboard
Intel Celeron E1200 - originally at 1.6 GHz (with idle around 41°C, with ASUS Triton Fan/cooler)
1GB Corsair originally @ 677 MHz
2x 512MB Kingston originally @ 677 MHz (both Kingston and Corsair with timings: 5-5-5-12)
It took me some tweaking, like:
Un-linking CPU FSB and RAM/PCI frequencies.
Setting CPU to 350 MHz (375 is ok too, I haven't fully tested it) with a 8x multiplier. 2.8 GHz and 3.0 GHz respectively.
RAM around 800 MHz
Turning on Intel Power Saver, turns frequency down when not in use.
With all of this, 2 case fans, ASUS Triton 77 cooler, I get around 45-46°C idle and 52-53°C on full load.
That should give you an idea on things, sometimes it's good to compare.
(P.S. the Celeron is using a Conroe base core, and M0 stepping. A Conroe M0 based C2D, gets around 2.7 GHz oc)
Best of luck to your pc!