P5Q Deluxe No Hard Disk Detected

My build has been very reliable over the past few years, but now a problem!
When booted I get the Asus flash screen then the following error...

I've heard of this error before but usually in new builds before the os is put on. I can't think of anything unusual that could have happened other than a crash, can't really remember there's no significantly new hardware in there.

Bringing me onto the specs

Intel E8400 CPU 3.0 ghz
Asus P5Q DeLUXE mobo
4gb OCZ Raptor X RAM PC2-6400 DDR2
ATI 4870 512 mb graphics
2X Seagate Barracuda 300 Gb Sata 300 hdd's
Enermax 82+ 600w PSU
some LG sata optical drive

I hope that's all the important stuff
Any help would be greatly appreciated!
If there's anything that I've missed that would be helpful please tell me!

Thanks!