This happens when the sav32.dat file inside the packages folder of SEPM CD1 folder is corrupted.
you can delete the 32bit MR4 package and then add MR5 Package.
Right click on 32bit 4000 package and delted it
at the bottom select add a client install package
it will ask for info files
now browse to SEPM folder of MR5 CD1
open packages folder, select sav32.dat file. it should add the packages.