I recently purchased a Sony Vaio Pro 13 Ultrabook with Windows 8 and I have an issue when connected to the VPN at work where it freezes every few minutes while using Remote Desktop through Juniper. After about 10 seconds it displays a dialog about the connection being lost and it retries and the connection is restored. Sometimes it happens so frequently that it is almost unusable.
I found a forum posting where several users are experiencing a similar issue with Windows 8 and Juniper:
I tried suggestions from this blog post but they did not resolve the issue: