Built-in Ethernet.. can it go bad?

At work I'm on a Mac Cube (refurbed). Our network is on DSL with a wireless lynksys router.

This morning I started up and I wasn't able to connect to the internet. It stated I was connected but that I had no IP address. Now I was fine yesterday. What can happen while being shutdown overnight to cause me to lose my IP address?

I restarted... twice.. nothing... unplugged the ethernet cable to the router and plugged it back in only to get a message that some other "computer" (long string of letters and numbers) was using it. Which I don't understand. I am guessing that string of numbers/letters is the ethernet card number, so I looked at the other numbers on the other computers here but none matched.

Well...... still fiddled around and for about an hour.. nothing. Then bam! I'm connected again......

So now I'm wondering if it's possible that the Ethernet card inside is going bad? is that possible?

If it connected I doubt it was the NIC in the Cube. From your message it sounds like some other computer took the IP address that the Mac was using. Is the Cube set for DHCP?

yeah it is but I checked the other computers and no one else was using the IP address that I had.

It's now assigned to another IP address *out of the blue* I dunno... just really weird. This had happened to my co-workers computer too. she's got a Power PC G4, she restarted and it was fine after a restart... didn't happen at the same time tho, this was about a month ago.