I have been using Recently Popular with success for WP 3.2.x. I upgraded to 3.3.1. Most plugins continue to work just fine. Recently popular for some reason de-activated itself and pulled itself from the widget column. I replaced it and now the web page stops loading leaving a partially complete web page. Removing the widget also causes the partial web page. Only de-activating the RP plugin restores full page load.
This is not the first time I have seem plugins cause this issue, but it has been a while. The only difference this time was a whole sale upgrade of plugins and WP to the latest version as of Feb 16, 2012.
I use the Prosense Blue theme with some custom modifications and that could also be a problem. I will research.