I'm using Debian and I'm connected to the internet via my wife's Win XP computer, Some websites work fine (This one for example) and yet others don't (www.halifax-online.co.uk, ebay.co.uk, qxl.co.uk). She can get the websites without any problems but I can't. Now how would I know whether it is her internet sharing that is messed up or my computer?

It is only a recent occurence, as I've only had debian for a week or so. But It may have been messed up before that as I didn't do much surfing in the last few weeks of using Slackware.

Oh, yes, uname -a gives me: Linux twosides.no-ip.org 2.4.26-1-k7 #1 Sat May 1 21:40:09 EST 2004 i686 GNU/Linux
and it is debian Sarge, if either of those help.

I am reminded of a similar problam a little while back whilst using Windows and I had accidently set my firewall to not allow certain things (maybe UDP?) which apparently these sites needed. Might this be the case and if so how do I solve this, I used "guarddog" to disable firewall altogether but this didn't help.

You're sort of onto the problem. I am no networking guru, but I have come across this problem before (although not with XP). How do you connect to the net? Is it with PPPoE? If so, you're probably losing packets due to timing out, where Path MTU discovery is turned off or not working. The servers you go to aren't resizingtheir packets to go through, as you're sending them the go-ahead for a full 1500 bit packet. That's my suspicion. I believe that you'll be able to resize your maximum segment size (mss) with the "route" command. I forget the syntax but I did figure it out from the man page. Look for yourself and i will try to figure it out again too. You may want to search www.broadbandreports.com for the proper segment size for your provider. It'll be a bit over 1400, likely. You want the biggest packet you can squeeze through without retries.

Cool, thanks. I used ifconfig instead, though. I did
when the device was already 'up'
it may not be 'optimal' but for now it solves the problem.

Once you find the best value, you can put it permanently in the config file. I think Debian stores that in /etc/network/interfaces, if I'm not mistaken.

The easiest way to find out is through trial and error. Increase the size of "ping" packets until the fragment and then back off. The biggest value before fragmentation will yeild your best results.. Good luck.