Strange problem

Well i just got a new Thermalright Ultima 90 and a G15 logitech KB.Well after installing the Ultima 90 and adding my G15 and putting my mouse on a usb port instead of the PS port everything seemed fine.But then Yesterday i come home from work and i cant boot my Computer.So finally i try clearing the cmos which worked .So i played with my PC yesterday and all was well and good.But then i come home tonight and the same thing.No boot now im like WTF.What would cause this it was running great before the Ultima 90 and the G15.This isnt the cold boot issuee with the HX620 and Abit IP35 series boards because with that you needt to warm the northbridge which doesnt help with this issue im having.Anyone else ever have this problem?.