Not sure if this is important but though I would add my experience.
I had the same issue using a desktop with 11.10, and a Tenda W54P wireless PCI card.
For unrelated reasons I removed it and started using a USB dongle (Edimax EW-7612UAn) and the problem went away.
With both of them I used the drivers which came with ubuntu so I would assume it is a problem with one of the wireless drivers. Unfortunately I have no idea how to check which driver was being used previously as I dont have the card anymore.
Not sure if this is important but though I would add my experience.
I had the same issue using a desktop with 11.10, and a Tenda W54P wireless PCI card.
For unrelated reasons I removed it and started using a USB dongle (Edimax EW-7612UAn) and the problem went away.
With both of them I used the drivers which came with ubuntu so I would assume it is a problem with one of the wireless drivers. Unfortunately I have no idea how to check which driver was being used previously as I dont have the card anymore.