It doesn't sound like you have a static. Who is your cable modem provider? If your losing it, it sounds to me its a dynamic and its trying to renew itself every half hour and its not properly doing that. If your suppose to have a static, I would be calling the ISP and telling them the situation. I don't think it might not be your own machine. I use to support RoadRunner and they did some screwy things to customers and have it so that type of crap happened all the time.
I use the LNE100TX card myself, if your using that one, goto this page http://www.linksys.com/support/support.asp?spid=25
They have good instructions on how to install the tulip driver for that card under Linux.
If you not using that one, check out their site. They are very Linux friendly. http://www.linksys.com
[Edited by trickykid on 05-17-2001 at 12:40 AM]