Hi,
I just tried to reproduce your problem down here, by upgrading a Vista 32 bits machine to the Tech Preview and wasn't able to see your issue, for me it works as expected. Of course that doesn't tell too much, as there are tons of ways on how your setup could be different.
Can you please attach the vmware.log files to a reply here? Maybe that will help in tracking down why you are seeing the problem with your mouse.
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Wil