My wireless connection drops in Ubuntu 8.1 32 bit after a while. I'm using a Linksys WUSB54AG interface. When it drops it loses its association with the access point. Then I've got to restart networking:

/etc/init.d/networking restart

and then re-associate with the AP:

iwconfig wlan0 ap off
iwconfig wlan0 ap any

From googling around it seems like this is common with Ubuntu 8.1 but I can't find any solution. Anybody out there know what I can do to fix this.

I've configured the interface to connect at boot, using /etc/network/interfaces and rc.local - I'm not using Network Manager.
It was connecting at boot but now its stopped and I have to do the three lines above to get it to connect. Today it went down and would not come back up but when I went into Windows (dual boot) everything was fine.

I'd be truly grateful for your help because I do a lot of unattended downloads (torrents etc) and I can't now because the connection continually drops.

Many thanks.