I had this problem a few times now. After creating a machine or updating to the current version of vmware workstation the drag and drop feature did not work anymore. This is used to put files from physical machine to the virtual and back.
The following post presented the solution:
http://blogs.aspguru.ch/stephan/archive/2008/11/26/vmware-workstation-drag-and-drop-problem.aspx
You just have to set the color quality of the virtual machine from „Medium (16 bit)“ colors to „Highest (32 bit)“ colors and it works again immediately.