Windows 7 Help Needed: PC Crashing with Blue Screen Error BCCode: 50

Hi,
Sometimes my pc crash and appear the blue screen, when i restart it a windows tell me that the pc has been restored and it show more information on problem:

BCCode: 50
BCP1: FFFFF898074D3B64
BCP2: 000000000000000
BCP3: FFFFF88004020CF7
BCP4: 000000000000005

OS Version: 6_1_7600
Service Pack: 0_0
Product: 256_1

who can help me to understand how resolve the problem??
sorry for my bad english but i'm italian