My internet connection has ceased to work.

Sort of.

I have a WRT54G2 router (the flat, sort of saucer-shaped one, see picture) that doesn't seem to be working right. I think. Maybe.

This morning I could not connect to the internet, so I went to a DOS prompt (OK, for you purists, a pseudo-DOS prompt, there is no DOS in Vista ) and found that I can quite reliably ping Google.com. I started my PingLogger program and for the past seven hours have not missed a single ping. My VOIP telephone (by OOMA, highly recommended) works just fine. My printer (which is also run through the router) works. But neither my computer nor SWMBO's Macintosh can connect. Nor can the downstairs neighbor's MacPro notebook, nor her iPod Touch. The latter two use the wireless aspect of the WRT54G2, while my computer and SWMBO's Mac are wired directly.

The topography is simple: Cable Modem --> WRT54G2 --> various devices. Everything seems in order, except that none of the computers will connect to the internet.

So... I bypassed the router and connected my computer directly to the cable modem (that's how I am writing this) and now nothing works internet-wise (printer, wireless, VOIP phone) except my computer. So the router seems to be the problem. I logged into the router (192.168.1.1) and all the settings seem to be correct, but what I know about routers and wireless connectivity is essentially... nothing.

If the router is broken when trying to use a browser (and we have tried four different browsers: Firefox, Internet Explorer, Safari, and Chrome, plus whatever an iPod Touch does to connect), but my DOS prompt shows connectivity, what does that mean?

I am way over my head here, and would welcome helpful suggestions.

tanstaafl.