I\'m getting this error:
tests.IntegrationTests.Selenium.RegisterAndLogin (TestFixtureSetUp): SetUp : OpenQA.Selenium.WebDriverException : Failed to start up
Which version of Selenium IDE you are using? Try downgrading the Firefox version. The release notes of selenium IDE is mentioned in below link.
https://code.google.com/p/selenium/wiki/SeIDEReleaseNotes
Hope this helps.