[ubuntu] Virtualbox unstable in 12.10?

Have been trying to run Windows 8 Pro (x86) in VirtualBox (Latest from standard sources + Patched) on 12.10 x64, for quite a while now, and it has been very unstable, using lots of CPU, locking up regularly (as well as locking up the host system) etc.
Am now running in openSuse 12.2 x64, (same VDI file/config) again in Virtualbox latest + patched, and it is running perfectly.
Anyone else experienced this?
Thanks.