PC Locks in Sleep. tried all i know :(

Problem(s). Not sure how related these are but ill start from boot up.
Bios says no OS, flashes, Bios again, then boots up. Bios is set to boot from the correct HD. but it boots up. not a big issue that i can tell, its just an FYI for the real issue that may or may not be related.

Real issue is the PC will not stay idle without issues. its very hit and miss. i leave the PC on 24/7 and it will have issues about once every 2 days.
the screen will be black, PC is powered (lights on PC, fans are running), no USB (i try plugging usb items in and no power). the PC will not wake up and i have to hold the pwr button to turn off.
I see nothing in the system logs and I've tried every power management setting including no power settings.
While the PC is locked the network is also locked. Any device connected to the home network has no internet connection including wifi.

If I'm using the PC, ill never have an issue, but leave it alone and it may or may not just lock up within ~2-72 hours.
Its always done this (a year now) and I've had enough and i cant figure it out myself.

Tried:
new router
adding more open ports (200)
changing power settings
updating mobo drivers /firmware
updating Video drivers
virus scans
reg fixes
installing keyboard drivers for logitech G15 (unable to do this, PC locks up during instal)

build:

Windows 7 Pro

1x Logitech Keyboard G15

1x

PSU CORSAIR|CMPSU-650TX 650W RT

1 x CPU THERMPASTE|AS5-3.5G %

1 x MEM 4Gx2|G.SKILL F3-12800CL9D-8GBXL

6 x CASE FAN SCYTHE USA|SY1225SL12H

1 x FAN CONTROLL NZXT|SEN-001LX RT

1 x CPU COOL CM|RR-UV8-XBU1-GP R

1 x MB ASUS P8P67 PRO LGA1155 R

1 x VGA EVGA|01G-P3-1561-AR GTX560 1G R

1 x CPU INTEL|CORE I5 2500K 3.3G 6M R

1x HD 160G|WD 7K 8M SATA2 WD1600AAJS % - OEM

1 x HD 2T|WD WD20EARS 64M % - OEM

1 x DVD BRN ASUS | DRW-24B1ST/BLK/B/AS% - OEM