Xen users - Sep 2014 - Network card disappears (probably xennet crash) on windows 7 pro 64 bit with gplpv

On one dom0 wheezy with xen 4.4-stable and xen-unstable and some linux 
and windows domUs I have had several times in recent months one or more 
windows domUs no longer reachable via the network.
In all cases the network card disappears and I must reboot windows to 
have the network working, I had also installed latest gplpv version 
(1.0.1100) that I saw that solves crash with xennet.sys but the problem 
persist.

If you need more informations and/or tests tell me and I'll post them.

Thanks for any reply.