Display/Mouse Freezing in VirtualBox on 14.04 LTS

Had difficulties getting VirtualBox to run after upgrading to 4.3.16, The resolution was to rebuild the kernel (see http://ubuntuforums.org/showthread.php?t=2245551).

However when running VirtualBox the mouse/screen keeps freezing for extended periods. It is particularly bad when running Word or Excel for example and I have even had to turn the ubuntu machine off on occasions.

The system shows no errors although something is obviously wrong.

I have interrogated the dystem re the video driver with the following output:-

john@tadw004:~$ sudo lshw -c video | grep 'configuration'
configuration: driver=radeon latency=0
john@tadw004:~$ sudo lshw -c video
*-display
description: VGA compatible controller
product: RV610 [Radeon HD 2400 PRO]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:01:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
configuration: driver=radeon latency=0
resources: irq:43 memory:d0000000-dfffffff memory:fe9f0000-fe9fffff ioport:dc00(size=256) memory:fea00000-fea1ffff
john@tadw004:~$

All ideas/assistance will be gratefully received