I have two examples now, my first two, where a place a RadComboBox on a web form, and populate it, but it won't drop down. I first picked this up on a big web application project, and then on a simple little web site project, for investigating this. In my sample project, it is the only control on the page besides the ScriptManager, and there are rows in the data source, and it does display the first row, but it just doesn't drop down. Any ideas on this?

BTW, this is theh first time I've restored this project onto a new XP machine, where I previously was working on a Vista machine that died.