I have not seen that error before. Please get this to the hotline.
In the meanwhile, the presets should be available in the left side of the screen. You should be able to recreate the workflow so this does not impact production.
Please make sure you are using the latest version of Silverlight: http://www.microsoft.com/getsilverlight/
When the web browser connects to FFCore, a silverlight client is downloaded to the browser. After upgrades, we tell the browser to flush the client from the cache. It seems silverlight will sometimes not honor this request. Please go to the About FreeFlow Core window and ensure the server and the client versions are the same
If the versions are not the same flush the IE cache.
To submit to the hotline (aka the Xerox Welcome Center) call 1-800-821-2797 with your serial number.