My knowledge of VM fusionware is zero.
No idea if this helps.
http://communities.vmware.com/message/526994;jsessionid=C2D96CCBD02BAD8BB75FB83180BAA84E
There is also a setting in ImgBurn; in the I/O tab - SPTI - Device Enumeration method, that could be worth to try the different options. 'Drive Letter' sometimes works better when you are using emulators.
You can read more in this guide about the above option.
http://forum.imgburn.com/index.php?showtopic=6232&st=0&p=65053entry65053