[Resolved] - Issue with my router DLink 704

[Megistal]

I have a problem with my router DLink 704 and I'm out of ideas now to correct the problem.

It work fine for my lan and for surfing on the net. But some sites get really laggy. One of them is windowsupdate. I downloaded an update of 1 meg in 15 minutes. (I have a dsl a 3Mbits / sec) That's not normal

A few sites that get really laggy because of the router.
Windowsupdate
hotmail
all ftp access

I've plug the external modem directly in the computer and all test was running at full speed.
I've also test the cables, (both one, from the modem to the router and from the router to the pc) and all cables are ok
I've try upgrading and downgrading the firmware of the router
My windowsXp is a fresh install w sp2 (I've also the same problem with win2k sp4)
I've also try the dmz host, nothing changed.

But bittorrent work flawlessly, at least

I don't know what to do to find what's wrong with the router.
As I said, I can surf on most web site but some like windowsupdate or hotmail are really laggy.

Any news ideas?
Thks