Assuming the machine is actually switched on, and you are logged in as domain admin, then try this below:
Installing clients using the Install Wizard will fail if the machine cannot be accessed remotely. This is usually to do with permissions issues in the registry.
You will need to do the following:
Go to the problem machine, open regedit and select following keys:
If the following keys don't exist please see
http://support.microsoft.com/default.aspx?kbid=314837
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurePipeServers
Ensure that the following groups have inherited permissions by right-click
the key and selecting permissions. If the check boxes are not selectable
and are grayed out then the permissions are inherited. If they are white
and selectable the click the advanced button and check the 'Inherit from
parent...' box.
(Machine Name)\Administrators - Full Control
CREATOR OWNER - Special Permissions = Full Control which applies to 'Subkeys
only'
Power Users - Read
SYSTEM - Full Control
(Machine Name)\Users - Read
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurePipeServers\winreg
Ensure the following groups do NOT have inherited permissions by
right-clicking the key and selecting permissions then click on the advanced
button and if checked uncheck the 'Inherit from parent...' box. The
following permissions are granted on this key.
(Machine Name)\Administrators - Full Control
(Machine Name)\Backup Operators - Special Permissions = Read which applies to 'This key only'
LOCAL SERVICE - Read
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurePipeServers\winreg
\AllowedPaths
Ensure the allowedpaths key is inheriting permissions by clicking the
'Inherit from parent...' box
Once the permissions are set, you should be able to install using the Install Wizard.