Speed troubles?

For the last 2 years i have been using giganews via Time Warner (roadrunner) with Grabit as my downloader. As of a few days ago my grabit download speeds have been around 17xx Kb/s..pretty fast.
Recently, I have been lucky to get 1/2 of that speed. Noting has been changed on my end as far as settings. When I deownload I kill all frewalls and virus stuff, so I know that stuff isn't to fault.
I have contacted both giganews and my ISP. Both say everything on their respective ends are OK. We've done traces, ping..etc, but no matter what I can not get my DL speeds back up.
If I use a speed test site I can confirm (roadrunner, msn, speedtest.com..etc) my speed at or above 1700 Kb/s. BUT if I use the giganews (http://www.giganews.com/test_connect.html) one I get only the 517Kb/s that Grabit reports while downloading.
Seeing this It seems my ISP is ok and giganews is wrong. Am I right?
I have sent the finding to giganews and hopefully they can see something they may of missed.

Any help from you all would help.

Thanks,
AJ

Actually it could still be your ISP or GigaNews, perhaps even the route. From what you have posted it sounds like there is throttling going on somewhere, maybe your ISP is throttling connections to the GigaNews servers or GigaNews have set a limit on your account. However, I have been using usenet for a long time and have never really heard that GigaNews limit people so more likely it's your ISP. Quite alot of ISPs have been known to throttle connections to usenet servers, sometimes they don't even tell you.

There is a possibility it could be the route between the GigaNews server and you too, one of the hops might be too slow or overloaded.

The only things I can recommend to you are:

Use different ports to see if it improves your speed (GigaNews allow ports 119, 80 and 23)
Enable SSL and see if your speed goes back to normal (Make sure you try both SSL ports 563 and 443)
Try a different usenet provider

If the problem persists then unfortunately your kind of stuck :(

Also in your post you were talking about traceroutes.. make sure you did a reverse traceroute (http://www.giganews.com/line_info.html). If you did a traceroute from you to the server that won't help much, that'll just show the route it takes when you upload ;)