Comment 34 for bug 374650

I don't think it has ever happened to me when using the wired connection but I rarely use it.

I have found the following to help a lot:

1. Install the Bleeding edge wireless drivers (every time the Kernel gets updated you must recompile and install them though)
2. Configure a static ip address on your wireless interface.
3. Use an access point that is not using wireless N (for me wireless N causes the problem more frequently)

Rather than rebooting you can right click on the wireless icon to uncheck "enable wireless" and then recheck it and you don't need to reboot the computer.