i try with ADMIN$ on the source machine
in my issue the problem was in the ADMIN$ (in my example the machine ip was 10.1.2.4 for lab testing)
after i solve the access denied problem ... all working
try to see error in the log file in Document and Setting\All Users\Application Data\ VMWare vCenter Converter Standalone\
you must try with command
"net use of machine\ADMIN$ /user:"administrator user" to see if there's problem of access denied
this was my "vmware-converter-server-3.log" file tell me
#2] 2009-04-09 13:20:38.046 'App' 3896 verbose Cached agent connection is for a different source, recreating connection
2009-04-09 13:20:38.046 'App' 3896 verbose Creating SOAP stub adapter for host 10.1.2.4:9089
2009-04-09 13:20:42.156 'App' 5484 info Install Agent on 10.1.2.4
2009-04-09 13:20:42.156 'App' 5484 info Connect to ADMIN$ on 10.1.2.4 as 10.1.2.4\utente
2009-04-09 13:22:00.218 'App' 5484 info SMB manager: Error connecting to share http://\\10.1.2.4\ADMIN$: 64
[#2] 2009-04-09 13:22:00.218 'App' 5484 error Deployment on 10.1.2.4 failed: Unspecified error in remote execution mechanism
2009-04-09 13:22:00.218 'App' 5484 error Install of Agent failed on 10.1.2.4
2009-04-09 13:22:00.218 'App' 5484 error Install Agent failed: converter.fault.AgentDeploymentFault
2009-04-09 13:22:00.218 'wizardController' 5484 verbose AgentManagerProxy::InstallAgent: Agent deployment status: 4.