I have what I think is a unique problem and has plagued me for months. Every search feels like I'm close to an answer, yet my problem is slightly different.
Three months ago, I acquired a d-link router. When I'm watching a video (youtube for example), it will load part way. If I want it to load another quarter, I have to open a second video. This gives the first video a wake up call and it continues to load. My internet (i.e. google), always loads/works.
There are times when I need to open 3-4 windows just so I can make the first video load. This usually occurs when the first youtube video is long. It happens with all videos...ranging from A&E, ABC, NBC, videos.
Recently I've begun playing MSN texas hold'em and the game begins to lag. In order to keep my connection to the game, I have to open up a video that is continuously loading or I risk being disconnected.
I've gone 3 months now like this, so it isn't an urgent answer...but oh my is it annoying. This only started when I bought the router. A direct connection from the internet provider to my computer fixes the problem. Also, I have the same problem in both Firefox and I.E.
What D-Link router do you have? My guess is that the D-Link router reboots from time to time and opening another page just triggers "resume" of the download. It's a problem I had when I first got my D-Link WBR-2310. Did you try flashing it with the latest firmware?