Go into Regedit (Start->Run, type in Regedit, click OK
go to :
HKEY_LOCAL_MACHINE\SOFTWARE\Activision\Star Trek Starfleet Command III
make sure that where it says CD that the Dirve letter is correct.. if not, then right click, select Modify and enter the correct drive letter...
Drive letter should be by default
D:
no slashes.
also make sure yor install patch is correct..
as such the default is :
InstallPath C:\PROGRA~1\ACTIVI~1\Sfc3
also make sure your install drive is the same as the CD drive
also check to make sure that the Version is 1.01, if it is not, you skipped installing the SFC 3 v500 patch.
Hope that this helps