I've recently faced an issue regarding using Provisioning Server (4.5, & 5.0) to provision XenApp VMs on XenServer hosts.

The VM's were booting properly and were responding correctly through XenCenter but was freezing when accessed through network (either ICA or RDP for example)

I had used all registry tips from KB (EnableOffload reg value turned to 0 ...) without any success getting my VM to work properly ...