virtualbox.org

PROBLEM:
BSOD (SYSTEM_SERVICE_EXCEPTION) with Host restart when trying to start VirtualBox Ubuntu Guest.

CONFIGURATION:
Host:
- Windows 7 64-bit Home Edition Extended
- Pentium (R) Dual-Core CPU T4400, 2.20 GHz
- RAM 4 Gb
Guest:
- Ubuntu 14.04 32-bit (with Mininet 2.2.1).
- RAM 512 Mb, Video RAM 12 Mb
VirtualBox: 4.3.26 r98988
Most VirtualBox options (such as 3D accelarators) are disabled

Could you help me to figure out what is happening and how to fix it?
If needed, additional info can be provided.

Thanks a lot in advance!