This error is seen when PDQ Deploy is unable to write to the target computer's ADMIN$ share (\\computer_name\admin$).
While this can be caused by many factors, this example is due to the trust relationship between the workstation and the primary domain failing. (Other causes may be firewall related, or if the workstation is not accessible on the network).
To determine the cause for your error, let's remove PDQ Deploy from the equation and generate this error manually.
From the console workstation (the computer where PDQ Deploy console is loaded, OR the PDQ Deploy Server if using PDQ Deploy Pro) try and whack into the ADMIN$ of the workstation experiencing the failure. In this step try whacking in using the hostname.
The following error appears:
You'll now see where PDQ Deploy is retrieving the error message. But this doesn't tell us why the admin$ is failing. To see if its the trust relationship, try step 2.
Try whacking into the offending workstation using the IP Address. It's here that you may see the domain problem.
If you see this error, the fastest way to fix it is to remove the workstation from the domain and rejoin.
Here is a Microsoft KB article which explains this process a little more.