I stumbled across a great png fix for IE 6: which can be found on this page.
I'm not a JS expert - I tried to see what the problem might be, but the complex code made no sense to me. So, I figured this error might be popping up because some images and css backgrounds doesn't have fixed width in them - so as an experiment I added width to all the appropriate elements, still same error, I tried inline width - still no luck.
The script works perfectly for me and faster than the htc alternative. Got any suggestions?
Note: I tried emailing the author, no response.