Screwy internet

Ok, so I probably should post this on another site with more specific people, but I generally like the people on the THG forumz more. So, here's my deal.

I have a Speedstream 5100b dsl modem and have SBC Yahoo dsl (advertised at 3mbps) and use a Linksys WRT54G router. It seems like about once a day I have to go upstairs to where my modem is and restart it because the intetet just dies. No reason, it just feels like dying. Sometimes I can go for like a week without having to do this, but on some days it might happen 3-4 times. It's really frustrating to be doing something and have the internet just stop working.
Also, (I just started having this problem) when I start using Ares or Azures, my internet will completely stop working for everything (and subsequently, every computer) except the one program (and sometimes AIM and YahooIM will keep working....) and will not come back on until the modem is restarted. Today, I had to restart my modem 5 times because of Azures/Ares related problems.
I've updated the firmware on both the router and modem and have the same problems.

Does anyone have any experience with these kinds of issues? or is this just a fluke? It really sucks not being able to use the internet and Azures at the same time.