Boot hangs at vboxsf.sys when vbox guest additions is installed

Hi
Since some months I have not been able to boot trunk after installing vbox guest additions. Boot stops at vboxsf.sys (vbox shared folders). Does anyone else experience this or is it my vbox settings? I'm a bit surprised someone else hasn't already filed a report on this yet so I suspect the later but I don't know what I can do wrong This used to work for me.