Can we get a link to the website?

do you mean that they work with ALL mac browsers but NONE of the Windows browsers?

or they just don't display in IE?

They just kind of fall apart, here's a screenshot. Unfortunately the site is on a developers server so I can't share a link.

Here's a better screen shot.

The blue select type shows best.

It looks like a hinting problem, but I wonder about the “loose dirt”. Is this a distressed font? That would probably explain why it renders as it does. If the EULA permits it, can you send me font file?

Frode's right, this is a hinting issue. I assume that in your TrueType generating preferences you have "autohint unhinted glyphs" checked. Try unchecking that and re0-generating the fonts. If this is a distressed font, it probably won't benefit from autohinting.

"...won't benefit from autohinting."

Might no even benefit from either unautohintng, de autohinting or hinting ;). Hard to tell...

Yes it is a distressed font, I had to take it into illustrator to tidy up un-closed vectors and clean it up but seems to still have the issue. I'm just about to retry and test.

Could you let us know what the original font is? Looking at the pictures you have posted I am (perhaps hastily) assuming that you did not part with cash or haggle over license terms...

The original font is Pound (http://www.myfonts.com/fonts/typodermic/pound/), And yes it was purchased with license for the client.

Have you tried contacting Ray Larabie? He regularly posts here and over on TypeDrawers.

Yeah, I've just sent him an email. Hopefully he'll be able to sort it and huge thanks to Frode for his help. He was spot on.