I have a Ubuntu 13.04 vm I build off the gallery image. I have updated the kernel to 3.9 (to resolve an issue with python-image-library).
It seems that after a few hours of working properly, all external network connectivity drops. I am able to send a restart command through the portal, and can see the graceful shutdown request in the local logs on the vm (so I know its not the vm locking up.).
After a reboot, all services work normally again.
Any suggestions to resolve this issue?