ASUS P8Z68-V - Difficult to boot! Please help!

hi all,
just build my new system with the following parts:
- ASUS P8Z68-V Motherboard
- Intel Core i5 2500 - 3.30GHz
- Corsair 8GB (4x 2GB) XMS3 Dominator Memory Kit - PC3-12800 - 1600MHz
- ASUS GeForce GTX 550 Ti DirectCU TOP Video Card - GDDR5 1024M
- Antec TruePower New Series TP-750 750W Power Supply
- Antec KUHLER FLOW CPU Cooler
- Antec Three Hundred Tower Gaming Case - Mid ATX Tower
- ASUS DRW-24B3LT 24x DVDRW
- Western Digital Caviar Blue WD5000AAKX 500GB
I have no any high knowledge about the new bios settings (just upgrade my old system with LGA 775), and I facing with a very frustrating situation: can't start the system....I just change the X.M.P from Auto to Manual, and I was able to run the OS, but, after several restarting, during of drivers installation in Windows, the computer stack again.....in order to start again, I have to start and stop couple of times from Power supply button. My question is: can I fix this and how ? thanks in advance for any answer and sorry if the subject has been requested...