Can't access certain sites

[#1]

Quote

It's definitely in some way related to my IP/Connection

You're on a dynamic IP address which changes each time you disconnect/reconnect so it's unlikely to be the cause as other people can access that site.
Can you access the site if you use a proxy such as http://www.megaproxy.com/freesurf/ ?

[#2]

Same problem here ever since I joined Plusnet.
Some days I can browse to the sites fine, the next I can't get on for hours at a time.
The main problem that is getting my goat is not being able to browse to www.odesk.com where most of my work comes from.
I can confirm that using the above mentioned proxy lets me on the site, but at this moment in time browsing bareback is returning just a blank white page.

[#3]

I tried tracert getsatisfaction.com and got pretty much the same result as swaymyway but the web page loaded very swiftly in Google Chrome.

[#4]

Sorry had not seen the additional replies!
Yes I can access the sites via proxies, but it doesn't help because I can't actually use the sites (as in log in, post comments, browse different pages etc).
Today I have another site to add to the list of those that won't load - zshare.net
I'm about to send in a ticket because it's at the point now where if I can't get it fixed I am going to have to switch to a new ISP.

[#5]

Have you tried adjusting your MTU / RWin?

[#6]

There is a type of computer virus that changes your DNS settings (sometimes).  If it's one of the TDSS family it can be extremely well hidden, so well that your security software may well not detect it (see http://www.prevx.com/blog/139/Tdss-rootkit-silently-owns-the-net.html). ; In my work on computers I see this virus quite frequently.  It is most obvious when you are using a search engine (like Google) and click on one of the links, only to find yourself at a completely different web site - but that doesn't always happen.  It can certainly render certain web sites inaccessible.  I have never looked to see if using a proxy defeats this virus but I guess it might.
The way to test for such s virus would be to borrow a "clean" computer, attach it to your router and see if it has the same problem.  If it doesn't then it's a problem with your computer, not with Plusnet.