You can configure Windows Vista to automatically delete the Roaming cache (copy of roaming profile) upon exit
To disable this feature:
- Click on Start > Run > regedit
- Go to:HKLM>Software>Policies>Microsoft>Windows\System
- Create a new Dword value and rename it as "DeleteRoamingCache"
- Double click on it and set its value to "1"
- Close registry.