Keyboard keeps cutting out.

About a two months ago my friend dropped my MacBook on the floor and completely wiped my hard drive. There is a little bit of aesthetic damage but after replacing the hard drive it's in working order. It's not as speedy or quiet as it used to be and the disk drive sounds like it struggles a little sometimes but generally the machine is fine.

I have had it on sleep for about two days and it's been in a very cold environment. Every two minutes or so my keyboard cuts out, the Num Lock/Caps Lock lights don't come on and none of the keys work. It's off for about 20 seconds then comes back but it's very frequent. Although while constantly typing the keyboard is fine, it's when it's not been used for about two minutes that it cuts out. This has only just been a problem since having the machine on sleep.

Would anybody be able to shed any light onto whether it could be the machine warming up after being very cold or if there could be a connection somewhere that's loose that hadn't become apparent until now.

If anyone could suggest anything that would be fantastic. Thank you.