My colleague Arno Meijroos was at a customer where they were experiencing disconnects when using Citrix Receiver 4.6. When the customer used Receiver 4.5 no disconnects occured.
NetScaler was running on Firmware version 126.96.36.199. An MPX was used.
Whilst looking at trace files on NetScaler and Client side all that was noticable was that the connection was terminated on the NetScaler side.
On the NetScaler custom cipher suites were defined to get an A+ rating in SSL Labs.