I'm using Ubuntu 10.04 on my laptop.
When I've finished a session, I just close the lid and the computer suspends. On opening the lid the computer normally finds my wi-fi network quickly and links up fine.
Sometimes, however, I get a red exclamation mark in the wi-fi icon (see image below) and the laptop doesn't try to search for the network for a couple of minutes. It does search eventually, but it is very slow if the red exclamation mark has cropped up.
Is there any way to stop this happening in the first place? If it does happen is there anything I can do to get the computer to start its search for the network?
Any help, much appreciated.