Ok, so the user is changing the laptops domain membership when he/she goes home, removing it from your domain and adding it to the home Workgroup? Is that what is going on?
IF so, then there will be problems one day.
The SID for the OS install ison the laptop, and when the laptop joins the domain, this SID info is sent to the domain controllers.
When you are in a Workgroup, you have a SID also.
But eventually, the SID is gonna get mangled from all of this changing, and the user won't beable to log into the domain. Then you will need to remove the laptop's account from the domain, so it can be added again, just like a brand new machine.
Basically, this is a problem just waiting to happen.
Work with the user and explain how they can still access their Workgroup machines from a Domain-member laptop. They might need to manually authenticate to the Workgroup machines (a BAT file with NET USE commands can make this automatic) to do so, but it will work. Plus, it really will be easier then all of this domain membership changing.
A single BAT file on the Dekstop that contains the IP addresses (or machine names) of the Workgroup machines, with valid Workgroup username/password, that manually authenticates to the IPC$ on each Workgroup machine.
The laptop user would bring the laptop home, log in using their Domain username and password, then double-click the BAT file. The BAT file will then talk to all Workgroup machines, authenticate with the Workgroup username and password, and then that is it!
The BAT file could also contain drive mappings to Workgroup shared folders. All in one double-click.
You see, it is easy to talk to non Domain machines from a Domain machine, if you know how to handle the authentication.
Feel free to send me a private message if you need help on writing the BAT file.
hope this helps