To avoid issues with any plugins like RoboForm or others that might cause problems, and to ensure you have a clean slate when doing UI testing, it would be worth considering doing what Selenium does when it spawns Firefox. It uses the -profile command line option to spawn the Firefox used for testing with a completely fresh profile (and you can force a specific one if you wish with a config option). That way you know it won't get messed up by any other features or plugins. It would be really good if the Telerik tools could do the same thing:

firefox.exe -profile "E:\myprofile" 

I also believe if you do this, it will spawn a brand new Firefox instance, so it won't interfere with an existing one that you might have running at the same time. 

Not sure if this is at all possible with IE, but if it is possible with IE that would be a welcome addition there as well.