The SolidWorks Flow Simulation can give you a message stating that authorization has failed. This is because on the client machine  the License Manager was opened and the License Order tab was selected. This changes a registry setting that needs to be corrected. Below is the work around for this and it has been corrected in 2010 SP3 which should be released in the middle of April.

Here is the workaround – please be sure you are comfortable editing the registry prior to attempting this procedure. Consider making a backup of the registry beforehand, in case you make a mistake.