Selenium 2 FireFox Webdriver - SSL This Connection is Untrusted

Anyone able to tell me why I keep getting the "This Connection is Untrusted" page when I run my Selenium 2 Webdriver test against a HTTPS URL?

My configuration is as follows:

* OS: Win7 SP1 64 bit

* Selenium: Java 2.33.0

* Java: 1.6.0_32

* FireFox: 13.0.1

Source code snippet:

File profileDir = new File("C:\\ -- FireFox profile DIR --");

FirefoxProfile profile = new FirefoxProfile(profileDir);

profile.setAcceptUntrustedCertificates(Boolean.TRUE);
profile.setAssumeUntrustedCertificateIssuer(Boolean.FALSE);

WebDriver driver = new FirefoxDriver(profile);
driver.get("https:// -- URL --");

driver.close();

All advice on the web indicates that this would be enough to supress the "This Connection is Untrusted" warning, but I am not having any luck.

Running the browser manually using the same profile does not display the Connection warning page.

Help appreciated