During the restore process, DiRT requires exclusive access to the UnityDB and ReportsDB databases in SQL so that it can restore the backed up versions of those databases.  If any application has a handle to either of these databases, the DiRT restore will pause and throw up a dialog box indicating it could not get exclusive access.  You are given the opportunity to exit out (which will put your system back into a running state as is) or hitting OK and trying again.  You can try again as often as you like, however an error is logged to the output file for each failed attempt.

Often it’s the case that the SA keeps a handle to the database around, even if it’s been closed.  This can take 20 minutes to clear which is often more time than folks want to wait.  The quickest way to clear all connections to SQL at this point is to simply stop the “MSSQLSERVER” and “SQLSERVERAGENTS” in the service control manager and then restart them.  Once you do this you can hit “OK” and try it again and DiRT should be able to get exclusive access and carry on.