virtualbox.org

virtualbox host is windows 2008 r2 sp1 and virtualbox 4.3.20 r96996

The instruction at 0x00000000 referenced memory at 0x00000000. The memory could not be written.

after opened few hours and got application error, few times per day
how to get fix of it? thanks

Hmm. Something jumped to a NULL function pointer. Since I don't recall anyone else reporting this problem with VirtualBox, I'd say this has to be a bug in a driver or other pervasive software on your host.

I suggest that you first try updating the GAs to 4.3.20. If that doesn't help then you could try reverting to VirtualBox 4.3.12, to see if the problem might be related to hardening issues - remember that it's especially important to replace the GAs when downgrading the VBox version.