There seems to be a problem with x authentication when you suspend at one location (home) and resume at another (work). In some cases, this move may cause your hostname to change, which will cause the X server to accept the clients, because they seem to originate at a different location.
This information is definitely insufficient (it's on my long-term to-do list), but at least you'll know you're not alone 
It may be solved by simply not letting your hostname being changed by the dhcp client.