Waking up from sleeping mode randomly disables network

I currently use a Toshiba laptop, Portege R830 14T, with a core i3 from Intel, with ubuntu 14.04.
I frequently wander from meeting to meeting, to office, to classes, etc. just closing the laptop lid. It happens randomly that network is off when I open the lid and there is no way of restoring it. My trick is closing the lid again and opening it:it usually brings the network back.
My question is:should this happen? Is there a way of either preventing it to happen or, alternatively, to restore the network when it happens?
Thanks.
A.M.

Laptops do a series of very complicated things in the suspend phase> I was witness to strong arguments in the early days, (on the linux-laptop list) when they tried APM, couldn't get it right, and went to acpi.

Make sure you have the Toshiba options for your box set in the kernel. Every laptop seems to have some acpi quirk. Have you tried 'ifup <network interface>'?