After having used Flash based text for the web for a couple of years, I stumbled upon a great script which makes implementing raster, rich typography on the web painless and very customizable. The script Cufón is one of my new favourites, and seems to be a healthy alternative to Flash text that works well in every modern day browser - even Internet Explorer 6 (IE6).
In our case, the error had been due to the PNG fix that was implemented for IE6 only. We have been using Unit PNG Fix, as well as Cufón on the same page - and the inclusion of both had caused some errors.
The FixOption 1:Change the order in which Cufón and Unit PNG Fix scripts are included. Call Cufón BEFORE Unit PNG fix.
<!-- Wrap the PNG fix in IE specific conditional statement -->
Option 2: It seems the problem can also be fixed in our case by using a different PNG fix, such as Supersleight (although I prefer Unit's fix).
I hope that helps someone out!