I understand that you are using visor image for installation(booting from USB).
USB booting doesnot provide a persistant scratch location.You need to point explicitly to a persistant scratch location.
Have a look @http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1033696
for creating persistant scratch partition.
Hope this helps
-SatyS