Custom Login Screen Not displaying after saving from inbuilt designer

Good Morning,

This morning i upgraded our instance of SDP to the latest version (10008) and noticed that there was a feature to allow you to customise the login screen using a inbuilt interface. I have done this by modifying a few of the colours and adding a little bit of extra text but left everything else as it is. The preview was displaying the screen exactly as i would like it to display. I have then saved these changes and logged out and now rather than displaying a login screen it just displays a blank white screen and i am not able to login at all. This now means that i am totally locked out of the software and unable to use it at all. Please can you advise on this as a matter or urgency so that we can get our system back up and running.

Thanks in advanced

Luke