Random Drop Outs with DI-624 - Router Issue?

I seem to be experiencing random connection drop outs when on my wireless network. The frequency is intermittent, but seems to be more prevalent when there are a lot of active users on the network. None of the other users seem to be experiencing this issue.

The strange thing is that when this happens, wireless strength will be at full bars, but I can't access anything on the internet.

Recycling airport (turning it off and on) solves the problem.

I had always been on a Ethernet connection until I moved, so I can't rule out the router. It's a Dlink DI-624 (4-5 years old) and I am running under WPA encryption.

1) Is it likely the router?
2) If so, what would be a suitable replacement in your opinion?
3) If not, what should I check?

Thanks.