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.

After working with Support Team for a while (and thanks for helping me solving this issue) they gave me the following Reg Value to implement into my Golden Image :

• Create registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\xenevtchn\Parameters
• Create a DWORD value called SetFlags in that key and set it to 20000 hexadecimal
• Reboot VM

In my case it solved the freezing issue.

After doing some researches on this flag it appears that this reg value is modifying XenTools drivers behaviour within the VM.

Actually the value above modifies the parameter of the scatter-gather implementation in the device drivers inside the virtual machine.