I'm including jQuery and a custom .js file into the master page of my SharePoint 2010 site. In the $(document).ready() function, I'm setting a live event handler on an element in the header of the page.
When I view the page, the jQuery event fires and processes the event correctly. If I edit the page and then save it, my event fires.
But if I edit the page and add a web part, for example the stock Images list web part for testing, the jQuery event no longer fires. jQuery and my custom file are still be included according to the dev tools source/script views.
Originally, I had the code being called repeatedly, every half-second, using setInterval(). That behaved the same way - it worked on every page until certain web parts were added. After that, it no longer worked until I edited the page again and removed the web part.
I say certain web parts because I haven't tried them all, but some, like the Calendar control, don't seem to cause the problem. The Images list always does.