I had the same problem.
Case – Moneual Labs 972, MB – Asus P7P55D-E Pro, PSU – Enermax EES620AWT, CPU – I5 750 2.66, RAM – 4GB (2x2) GSkill GSK F3-12800CL9D-4GBNQ, GPU – MSI 5450, W7 Ultimate 64bit
Problem#1
I put the computer into sleep from the power button on the case, killed my TV/Monitor assuming things would go as usual, went to bed. Next day, turned on my TV and noticed HTPC’s power was still on, with both the case and TV screen displaying only a black screen, and the HDD indicator on case was pegged (accessing/thinking). Couldn’t get W7 to come back and only option was to hold power button for 5 sec to turn off. Then nothing worked at all, like it was fried. Opened case and the only signs of life I could get was a green led on the MB and one on the back of the touch screen. Jumped the PSU and it worked so that was ruled out.
Fix #1
Reset CMOS. Refer to the MB manual for instructions. Just moving the jumper didn’t work for me, so I had to remove the battery too. Computer fired up first time after resetting, but…
Problem #2
…when starting W7, computer freezes on the Windows logo pulsating splash screen. The 4 colored orbs fly into place and pulse for about 5 seconds, then freeze and no longer pulse. I tried just about everything under the sun in BIOS settings, startup options, PS/2 keyboard w/ no mouse, etc. I could get W7 to load but only in safe mode, however the same problem always occurred when trying a ‘normal’ boot. Also tried booting/reinstalling from W7 disc with same problem.
Fix #2
Powered off computer. Removed 2nd RAM chip from MB. Started computer and worked first time. Then powered off computer and reinserted RAM. W7 loads, works as it should, and all 4GB RAM show in BIOS.