This issue is fixed in the following versions:
Pulse Desktop client 5.3R6 and up
Pulse Desktop client 9.0R2 and up
(Note: It is not necessary to upgrade the PCS OS server version in order to get the fix. Only the Pulse desktop client needs to be updated).
As a workaround, negative DNS caching can be disabled in the registry. See How to Disable Client-Side DNS Caching in Windows XP and Windows Server 2003