Failing Hard Drive?

Thanks to the help of Tom's community last year, I built my machine and it was running sweet until recently. Computer has been crashing of late, especially when it's cold. Once it warms up it runs smooth.

The symptoms of the crashes are: everything freezes, then I restart it, and when it boots up 99% of the time it says this ""reboot and select proper boot device
or insert boot media in selected boot device"

So I would turn the power off for about 3 seconds and turn it back on again. Lo and behold! It reboots without that message.

Just wondering if anyone has any idea about what's going on? I suspect that my hard drive might be failing but I am not too keen to buy another drive and transferring files. Hope that there might be a dirty and easy way to fix this!

run some tests and check your cabling first before coming to any conclusions