I have a Windows 7 64 bit client on a workgroup. My other computers are XP professional. Weekly, I back up each client to my Windows 7 folder which is shared on our network. I usually get about 6 of 12 pcs to backup to my machine using Acronis before access to the shared folder is denied. Initially I thought that the firewall or Symantec Endpoint was the cause, but removing Symantec Entpoint Protection( Latest MP2) did not help. I enabled guest accounts on all of the XP machines and the Win7 machine too. I Wanted Microsoft to be aware of this issue to see if there is a known fix. Seems like a reboot of the WIN7 machine restores access, but I don't know why. I never had a problem before when my machine was running XP pro.