Technical Help?!

So in the last few days my DSL has just started fritzing out intermittently. No rhyme or reason, it's gone for a few minutes and then I click and it's back up again -- about fifty times a day. Rebooting the modem and router doesn't seem to make any difference. XP doesn't notify me when the connection is down, or admit that there's anything wrong with the network, but while it's on the blink, none of my internet-capable programs work (so it's not just a browser issue).

Does anybody have an idea what might be wrong here or where to start troubleshooting?