I have ran across this issue a few times myself, as well as some of the Mac users here. 

A few things that may/may not help.

Network name of the Mac-  Apparently some 2wires freak out because the network name (machine name) isn't proper or uses non-standard characters. This apparently drives the 2wire nuts.

Changing the base IP address from a 192.168.x.x to say a 172.16.0.x or another base address- Apparently someone I worked with a while ago found that his Mac was arp'ing the (&^$%*(%&*$) out of the base address causing the 2wire to shut down/reboot because the 2wire think's it was being attacked.  I never did find out which version of the O/S that was but one clue we did discover is the 2wire was reporting a attack from an internal address in it's logs.He did open up a Genius Bar ticket on this and he would e-mail me back if he ever got an answer as to why, but so far I haven't gotten anything back.

Change the 2wire's wireless channel- Most 2wires come on a default  channel 6. If there is other more powerful devices on those channels it might be just be plain wireless noise. Now for windows there is a utility called "netstumbler" you can run and see what channels are occupied. The idea here is simple, find the channel not showing up and use that one.

Watch the number of ports that are open- Had another instance where the Mac was opening up too many ports on the 2wire and the 2wire would just reboot and drop the connection. This one happend on wireless as well as wired.

Again keep in mind these are tips that may/may not help.