Did you definately set the router to factory settings by pressing the button on the router not just the reset inside the configuration bit of setup ?
If its any comsolation, it took me a couple of days to set mine up and I even had someone on line helping me and another friend came round and we couldnt sort it out.
Just before I went to bed that night I reset it to factory defaults entered the details as I posted earlier, still didnt work so I switched everything off and went to bed.
The following morning I decided to see if it would connect before I went back to the modem and it worked perfectly ever since
It seems that although I had saved the router settings and rebooted it many times it juss needed the pc to be off as well as the router and when they were switched on together it sorted itself out
I suppose theres always the possibilty that you have got a faulty router