Message:

An error occurred initializing PACS. Please notify support.

Could not load file or assembly 'Interop.RadWhereAxLib, Version =1.0.0.0,
Culture=neutral, PublicKeyToken=null' or one of its dependencies. The
system cannot find the file specified.

Launching the Client, the following message displays:

This is a problem loading one of the files from the %LocalAppData%\Apps\2.0 folder.

Remove the Apps\2.0 folder and let it repopulate on next Client launch.