We have two clients. They are using different versions of Citrix. We don't know what versions of Citrix servers they are using but we are using citrix client version 9 and 4 to connect to their servers. The task is to use one citrix client version 9 to connect both clients' servers for more flexibility. When we try to use citrix client version 9 instead of version 4 all users freeze. My question is what can be a reason why all users freeze? What we can do to resolve it?