"Install Guest Additions" hangs VirtualBox 4.1.8

[mrelwood]

Newbie here, installed VirtualBox today for the first time.

Trying to install Guest Additions in order to get fullscreen display. Choosing "Install Guest Additions" from the Devices menu, or navigating to the separately downloaded .iso as a virtual CD image, both hang the VirtualBox VM and VirtualBox applications and only give me the beachball. Starting the VM in safe mode gives the same result. At this time Cmd Tab no longer works even in other OSX applications. Force quitting the VM makes both VirtualBox and the OSX normally usable again.

Installing the guest OS didn't go smoothly, the installer got stuck at the "Expanding Windows files (0%...)" and had to be terminated. I installed Windows on top of the failed install, so no traces should be left from the interrupted install.

Using:
OSX 10.7.2. Lion on a mid 2010 MacBook Pro 15"
VirtualBox 4.1.8 for OSX, running Windows 7 64-bit.

[mrelwood]

Update to above: I created a new VM and installed Windows 7 as a 32-bit version. Now the Guest Additions does work, as well as trackpad scrolling.

Wether the issue was with the 64-bit Windows or a corrupted install.