My FNV Was Working Well Before Then Suddenly It Gives This Error Which I Dont Know How It Happened

Problem signature:
Problem Event Name: APPCRASH
Application Name: FalloutNV.exe
Application Version: 1.4.0.525
Application Timestamp: 4e0d50ed
Fault Module Name: ntdll.dll
Fault Module Version: 6.1.7601.24384
Fault Module Timestamp: 5c6e2180
Exception Code: c0000005
Exception Offset: 00063289
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 67a0
Additional Information 2: 67a08da2ebf8307e1c141b52756bc0ca
Additional Information 3: b883
Additional Information 4: b8837dff7c25ce87b3f3a0a32aea1862

Any One Know What Is The Problem Any Other Game Working Well
Hope Someone Know Solution