Some time ago I was converting a virtual domain with vm’s in Microsoft vmc(vhd)-format to VMware’s vmx(vmdk)-format. Some of them worked right out of the box after converting them. Others did not work, to be specific they worked up to some point at least they seemed to freeze when sending CTRL-ALT-DEL.
The strange thing was that not all but just a few of the vm’s of the converted domain were "freezing". Taking a closer look at the operating systems I noticed the servers were running different versions of Windows 2003 server: enterprise vs standard. But this still did not explain the strange behaviour.
I used the vm’s in a VMware Server scenario. Connecting to them using the VMware Server Console resulted in a freeze (no reaction to keyboard and mouse). By converting the vm’s to VMware format they received new unconfigured network adapters (they were set to DHCP). The fact they got a dhcp-address saved me some work.
Using RDP I was able to connect to the vm’s (on their dhcp address). Connecting like this worked straight away, no freeze occurred. Thats what triggered me to look at the VM additions from Microsoft.
Looking at the drivers for the mouse and keyboard I noticed that they used the Microsoft Vm additions drivers. I managed to fix the issue to roll back the drivers, for both the keyboard and the mouse. After a roll-back of the mouse and keyboard drivers and a reboot of the server I was able to control the vm’s again using the vmware console.