Under linux on 5 different machines and two browsers I have issues connecting to three sites, www.pastebin.ca, www.openldap.org, and the site the "go" button on www.pcfinancial.ca goes to. Under firefox, they take an age to load, but might eventually actually load. Under konqueror the pcfinancial link immediately fails with a "connection to server refused" error, and the other two take 30 seconds or more to give the same error. OSX is almost identical. But windows works perfectly fine for all sites.

I've tested with linux and windows, inside and outside of my network and the only two conclusions I can come up with so far are:
1. linux and OSX are somehow broken (or more picky?)
2. My ISP has a strange problem that doesn't manifest itself under windows (the only OS they support, so its unlikely they'll give me the time of day).

Has anyone ever seen anything like this?

As a side note I've tested Debian Etch, Debian Sid, and an OpenSuse 11.1 LiveCD, OSX and Windows XP. I've tested Debian Sid on 3+ computers, Debian Etch on 2+, OSX on one, OpenSuse on one, and XP on 3 (laptop, desktop, and desktop under VirtualBox). No matter how I test it, and where, the only common point is only XP seems to work properly.

It appears wget can connect to them just fine, and download the index. I'm totally confused.

Ok, it appears openldap.org and pastebin.ca both have ipv6 addresses, and my LAN is ipv6 enabled, but my WAN (internet) isn't, so it'd sit and wait, and wait and wait for ipv6 to time out, but the browsers quit before that happens. Once I disabled ipv6 on my desktop both of those sites are working fine. All thats left is my online banking's https section. Its slow (<1K/s, connects take 10s of seconds) in firefox, and errors in konqueror (3 and 4). But in windows, its speedy. Same LAN.

Goto about:config in firefox
Set the filter to ipv6
Change the variable network.dns.disableIPv6 to true
Restart firefox.
Better?

Thanks for the tip, I already disabled ipv6 on my machine, which as I mentioned, fixed two of the sites. All thats left is my online banking site thats only acting up under linux. Slow in firefox, won't even connect in konqueror. It immediately gives a "Connection to server refused" error.

this is the url.

That site is glacially s-l-o-w, using both konqueror (which I set to report itself to the site as IE6 on win XP)
and firefox (2.0.0.19 and IPv6 disabled) - so slow, that nothing loaded during the time (minutes) that I was prepared to wait.

I suggest you contact your bank and complain. I complained to mine (in UK) about "This site needs IE" when it did not (I just spoofed IE's "Browser ID" to get it to work), and they fixed it fast. The last thing a bank needs is users running IE - I never use windows for banking.

It could also be that your bank does not allow access from this side of the pond, but I doubt it.

Funny thing is its fast as it should be on my laptop when its booted into XP. IE and Firefox have no issues. Until I try under linux that is.