signor :
possibly failing to return from sleep/screensaver mode. Is this a desktop or laptop, if so does it meet the required specs.
Check that you definitely have all the latest drivers and that they are all actually for win 7. Main drivers to check are chipset, audio and graphics.
Disable sleep/screensaver/hibernation and see if the issue persists. If not if you have only changed your OS and not changed anything in your built either run the repair utility for windows via the installation disk/iso or alternatively give it a fresh install.
thanks
sig
desktop
processor
AMD A8-3870K Unlocked Llano 3.0GHz Socket FM1 100W Quad-Core Desktop APU with DirectX 11 Graphic AMD Radeon HD 6550D AD3870WNGXBOX
Hard drive
Seagate Barracuda 2 TB,Internal,5900 RPM (ST2000DL003) Hard Drive
cd drive
SAMSUNG Black 12X BD-ROM 16X DVD-/+R 48X CD-ROM SATA Internal Blu-ray Combo Model SH-B123L/RSBP LightScribe Support
RamX2
G.SKILL Ripjaws X Series 8GB 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Desktop Memory Model F3-10666CL9S-8GBXL
Power supply
Rosewill Xtreme Series RX750-S-B 750W Continuous @40°C ,80 PLUS Certified, ATX12V v2.2 & EPS12V v2.91, SLI Ready CrossFire Ready, Active PFC Compatible with Core i7, i5 Power Supply
Motherboard
GIGABYTE GA-A75-UD4H FM1 AMD A75 (Hudson D3) HDMI SATA 6Gb/s USB 3.0 ATX AMD Motherboard
Tower
Rosewill THOR V2-White Edition, THOR V2-W Gaming ATX Full Tower Computer Case, support up to E-ATX / XL-ATX, come with Four Fans
Graphics card
HIS AMD Radeon HD 6970 (H697F2G2M) 2 GB GDDR5 SDRAM PCI Express 2.1 x16
gona set up crossfire with apu when i get it all set up