I'm sure it does Paul, I certainly didn't mean to offend.
Basically, I upgraded to 3.7 and then made an effort to upgrade all my hacks. All seemed perfectly fine until someone mentioned to me that the default calendar for the board was drawing a blank page.
So I began turning them off one by one and testing it. The default board calendar would not come up until I got to the unread posts hack. I realize there is probably nothing wrong with your hack, just that they may conflict somehow...not sure. I could be crazy. LOL
Here is a link to my board:
http://www.thedarktower.com/palaver
My members are going crazy without the "unread posts" modification so I'm putting it back on no matter what, calendar or no.