The netsetup.log in Windows 7 (c:\windows\debug) should give you an error as to why the join domain fails.
I am having this same issue. However, I am able to join to the domain when the "Add device to an active directory OU" is left unchecked. You may want to try unchecking that box if you currently have it checked.
Domain joins depend on your Domain. No OU location speficied and no Computer account precreated and If your Domain Admins have disabled the default Computer OU in AD will cause failure.
Also Vista/Win 7 no longer support failure Domain join stop in Sysprep.
Sugestion as atest. Pre Create the computer account in AD OU and set for a <your domain>Domain user to join. This als requires a domain account and Password in the unattend.xml under the AutoJoin catalog item.
I am assuming you are doing domain join in unattend.xml, if you are doing it in a Provisioning task, similar concept applies.
Sorry if I added confusion
I recommend you talk to your domain admin and have them create a test OU and a service account that has the permissions to add computers to that OU. For the most part, domain admin disable the Computers OU to prevent rouge devices in the domain. In addition, that user account should also be part of the Scheduler service under Configure services in your Landesk Console.
If you ever go into Production, I recommend you use Public variables for your Domain, User account, password, Image share. This will secure your unattend.xml. Once your provisioning script is deployed, have a task that deletes the unattend.xml leaving no trace of your passwords. Keep us posted of the outcome.