Fedora Users — FC2 locking up randomly

This has only just started happening. I have had the server (which is currently being co-lo'ed) running for 6-7 months and it now randomly freezes completely. Last week I updated to the 2.6.9-1.3 fc2 kernel and about 4 days after that it started freezing. I thought there must be a connection, so I then upgraded to 2.6.9-1.6 kernel, still happening. I set grub to boot from one of the older kernels I had been running for months on and it's still doing it.

Twice today now. All fans were working and temperatures were the same as before. Had top open, memory usage stayed roughly the same, no new processes, cpu stayed at about 35%

I'm waiting for redbus to reboot it then I can run memtest but I think that will come back ok.

Any thoughts?

Cheers,
Tim