Good morning,
I ran into a problem when I tried to upgrade Workstation 6.0.5 to 6.5.1. The upgrade itself went fine and my existing virtual machine came up 'normally'. Then the fun began 
First, some descriptive information. My host system is RHEL5 (kernel 2.6.18-92.1.22.el5PAE) running on a Dell XPS600 with 4GB RAM and with an NVIDIA Geforce 8700 video card (driving a Dell 30" monitor at 2560x1600 resolution). My virtual machine is installed on a 120GB virtual disk (stored on a 150GB SATA disk that has nothing else on it) with 1.5GB RAM assigned to it. The Guest operating system is Windows XP SP3. This configuration runs fine under Workstation 6.0.5.
After upgrading Workstation and bringing up the client I attempted to install the new VMTools. During this installation, I was informated that the following drivers could not be installed and needed to be installed manually: SVGA, mouse, vmxnet, scsi, and a bus adapter (may be related to scsi---this wasn't entirely clear). When I attempted to do the manual installation of any of these, it would fail with a "file not found" error message.
In this state, the virtual machine could not see the network (I used a bridged network configuration with the VM having its own IP address). The video configuration appeared to be ok in that the resolution was what I expected it to be (2048x1024). The mouse had a tendency to jump around a lot and was hard to control.
I tried upgrading the virtual machine to 6.5 but no joy. I manually uninstalling Workstation, rebooting the host system, and re-installing but got the same messages. I tried uninstalling 6.5.1 and installing 6.5.0-same effect. I finally went back to 6.0.5 (this required going to a backup of the virtual disk to get back to the 6.0 virtual machine); this worked fine and my virtual machine is back up-this is where I am right now.
Has anyone else bumped into this situation? And come up with a solution?
Thanks!