If you have Windows 2008 R2 as a VMGuest and you find when you use the viclient console the machine locks up and a hard boot seems to be the only fix.
The issue lies with the video driver bundled with the vmtools in vSphere 4.0, 4.0 u1, and 4.1. The video drivers were fixed in the 4.0 u2 vmtools. Huh? 4.1 came after 4.0 u2 you say. It did and after discovering this I confirmed with an SE at vmware that indeed the drivers that were bundled into 4.1 predated the video drivers that were released in 4.0 u2. This will be fixed with the next update release for 4.1 but in the meantime, one fix for the issue is to install video drivers from a 4.0 u2 vmtool install.
1. The VMware Tools install should have created the folder: C:/Program Files/Common Files/VMware/Drivers/wddm_video.
2. Browse to your Device Manager, choose your video adapter, right click, and "Update Driver".
3. Browse to the folder listed above, reboot.
4. At this point it should be fixed.
5. If it is not fixed, shutdown your VM, go to edit settings, click on Video, and verify is has 8MB of Memory for Video.
6. You may also need to verify this in the BIOS.
I hope this helps!