PC Only Boots If I Press Restart???

Ok I unplugged my hdd and cold booted three times in a row, no problem.:)
Then I plugged it back in and cold booted, no problem. :O_o1:
Tried it again, worked fine. Tried it a third time and it didn't post. Unplugged the hdd again to make sure it definately was the drive and guess what, this time it didn't post. After 10 mins of plugging and unplugging different hdd's it seems there is no pattern to this behaviour. Sometimes it posts fine with or without any hdd's plugged in, sometimes it doesn't. Sometimes it posts while the system is still on after making a change to the bios, sometimes it doesn't. Seems to me this issue isn't related to my hdds. What next???:help:

I've seen this issue when googling my W7 sleep issues. (Won't wake up) There are apparently settings in the BIOS (S1, S2, S3) which affect the power management settings and can cause symptoms like this. I'll see if I can find it again.

EDIT: Something related to this power management settings ?
http://superuser.com/questions/49130...-up-from-sleep

I did try playing with these bios settings however seeing as this happens on boot as well as resume it doesn't seem like an s3 issue.