STAAD Offshore Error 1603

I'm trying to reload STAAD and STAAD Offshore after a clean up of my hard drive. The latest version of STAAD installs fine (stpst20071190en) but I get the following error with STAAD Offshore:

"Bentley OpenSTAAD OEM [08.02.09.25] (error 1603)"

I seem to vaguely recall this from the initial install but cannot recall how to overcome it. Also can't seen anything on the forums.

Any help much appreciated.

Regards,

Barry