flakey internet access through network

["" <postid@BasicISP.net>]

I'm working on our school's computer system and discovering that the internet access is really a pain. I can log on to the wireless  network and get a strong signal, but internet access comes and goes. I just discovered that if I try to do a search, click on something online, or start writing a webmail email, it will just try and try and then finally give up trying to access the internet. If I start a process, however, then in a console enter

# dhclient eth2

Bingo! the internet responds.

Otherwise I just have to wait until it comes back, which could be five minutes or 20 minutes or whatever. 

What's happening here? Is it forgetting that I'm logged in? 

The commands I use for the initial connection are:

# iwconfig eth2 essid "NAMEHERE"
# iwconfig eth2 mode Managed key open
# iwconfig eth2 key KEYHERE
# iwconfig eth2 dhclient eth2

I was doing a netinstall here (with a wired connection on this network) a few nights ago and it was taking forever because I'd lose the internet and have to wait for it to come back again and continue the download. Sometimes I'd still have internet access on one of the desktops and on my laptop, sometimes just the laptop, sometimes just the desktop, sometimes just the wired computer involved in a netinstall.

What's going on here? How do I solve this problem, at least for my laptop and the machine on which I'm installing lenny? My laptop is running Debian Sarge (it'll get lenny when I finish here), I'm trying to install lenny on one of the desktops, and everything else is windows.

postid