Hi,
The issue is most probably because you have set different Protected Modes in Internet Explorer.
The error you'll first see is
"5134 [pool-1-thread-1] ERROR net.thucydides.core.webdriver.WebDriverFacade - FAILED TO CREATE NEW WEBDRIVER_DRIVER INSTANCE class org.openqa.selenium.ie.InternetExplorerDriver: Could not instantiate class org.openqa.selenium.ie.InternetExplorerDriver
net.thucydides.core.webdriver.UnsupportedDriverException: Could not instantiate class org.openqa.selenium.ie.InternetExplorerDriver"
But somewhere you should see also this error "Protected Mode settings are not the same for all zones. Enable Protected Mode must be set to the same value (enabled or disabled) for all zones"
Go Internet Explorer > Internet Options > Security and set same Protected Mode for all zones (i.e. Internet, Local intranet, Trusted sites, Restricted sites): either enabled or disabled for all of them.
Then try to run again your test cases. Hope this helps, that was the issue in my particular case.
Cheers
Theo