On XenApp 6.5 you might see a long delay when reconnecting to a published desktop, and the desktop was locked when disconnected. The user will during the delay just see a black screen:
In the event log on the XenApp server you will see an event ID 1009 from the source picadm.
I have seen this on XenApp 6.5 servers with hotfix XA650R01W2K8R2X64002 or XA650R01W2K8R2X64090 installed.
For now the only solution I have been able to find is to remove the installed hotfix.
Lets hope this will be fixed in a later hotfix.
UPDATE 04-07-2013
Hotfix Rollup Pack 2 fixes this issue 
Attempts to reconnect to a locked, disconnected session running on a server where Fix #LA1817 is installed might take about two minutes.
[From XA650W2K8R2X64R02]
http://support.citrix.com/article/CTX136248
I can confirm that this is now working as expected.
