Found a minor bug which is primarily a user problem, but it throws an unhandled exception when trying to browse HTML on an unsaved, non-existent page.
Steps to reproduce (100% repeatable):
1. Enter a non-existent web-page into the file field: (i.e.: doesntexist.htm)
2. Select File->Browse HTML
3. Error occurs
I came across this as I was building a new page, I changed the File entry but hadn't left the field yet, got distracted by a phone call and then came back to AC. Because I hadn't left the field yet, the unsaved * hadn't appeared in the title bar yet, so I thought I had already completed the page and saved. Tried to Browse HTML, and received the unhandled exception. Options are to "Continue" or "Quit" with quit being the default option. Continue returns to AC normally, but it would be nice to have that handled in a manner that does not have a default quit option.

It probably happens for similar options in the file menu, but I didn't test them.
It could easily stay as is and be fine, in the six months I've been using the tool, this is the first time I've encountered it, but wanted to bring it to you attention in case you want to wrap the error in your next build.
Wolfschadowe.