Can i have some hardware help?

right I'm a bit of a noob at hardware and new to the forum  so my fault if I'm a bit of and idiot and I didn't know where to post it.  i got my computer to boot windows and it was running really badly and slow in task manager it was telling me that my disc was constantly at 100% then after a while about 3 minuets the screen flicked and it logged me out does this mean i need to replace my hard drive  

Might be the hard drive, might be Windows itself. It's hard to say. 

  I would start with formatting the drive and re-installing windows... then move on from there depending on the results...

can also be spyware or virus.

But is your disk at 100% or is your CPU ussage 100%?

had the same problem for a while. Turned out to be my Raidcontroller doing some heavy SMART testing... changed the schedules and it's all fine now :) I imagine this is not your case but IF it is, try disabling SMART monitoring in the BIOS/UEFI.

It could also be an antivirus of some sort doing some kind of scanning.