Error: access violation at 0x05C94271 (tried to write to 0x00000000), program terminated.

I am getting this error in my virtual machine. I have Windows 7 64 bits. What should I do now? Does somebody face this error before? If than let me know please. Thanks in advance

Error
Error: access violation at 0x05C94271 (tried to write to 0x00000000), program terminated.
