I've had the same issue on two out of six Windows XP desktops that I've had to reinstall MAS 200 v4.40 Workstation software on.  All desktops are XP SP3 and current on WIndows patches.  The other four XP desktops had no issues re-installing the MAS 200 workstation software.

It looks like the install is going fine.  It takes 2 or 3 minutes for the progress bar to get all the way across (ie: 100%), but then it just sits there forever.  No errors are displayed.  If I go into task manager and kill the process, and then look in Add/Remove Programs, the Sage software is not shown on the list of installed programs.  I cannot launch MAS 200 on the affected machines either.

Deleting the C:/Program Files/Sage Software folder, and trying the install again yields the same result, with the install wizard hanging just when it looks like it is completing.

Any ideas ?