Well, thanks to his help with the coding, the second URL button I added to the template (the one that pops up a javascript input box) is no longer creating errors in the forum log.

For some reason, it still causes an error symbol to show in the bottom left corner of my browser window when I roll the mouse across it (I'm using IE 6.0 ), but we haven't worked out why that is yet.
The important thing is it's not recording any errors in the database, so maybe it's a browser-specific thing.
