When using my Blackberry web browser I try to access a site and get an error:

WAP Session Abort 1: The WAP gateway could not interpret a PDU

What is a PDU? Do any of you know why this site might not load?

The site in question is:
http://www.eudesign.com/chessops

I searched for PDU and didn't find any info on the boards so I'm sorry if this is something that has been discussed before. I am just curious about what that error means.

Protocol Data Unit. Its just the generic terminology for a message being delivered to/sent from you (MIME, for example, I believe).

...and to answer your question on WHY, its most likely just that the handheld simply cannot decypher the data being sent to it. Think of it like you speaking a Korean man on the phone who cannot speak English (unless you speak Korean, in which case, bad example).