Unclear on the Concept

I'm jumping through various hoops to register on the forum of a vendor (who shall remain unnamed) in order to post a question, when I strike this error:

Unclear on the concept

For those of you who can't read the wonderful colour scheme, the message reads:

There was a problem with your details.

You may not use any of these chars in your password !#%^&*()=+{}[]|\;:/?>,<'

Kinda makes it more difficult to create a secure password.