Have you tried with an old version of SWPM before the new one?
You shouldn't get the option with EHP5 with a brand new SWPM.
Í have experienced that, on the windows platform, temporary files where used despite the fact that a new version of SWPM was used. Turned out to be (in my case):
1 - an old "swpm-log-console" (can't remember the exact name) was running.
2 - closed that console.
3 - removed temporary files (In my case C:\Users\<adminuser>\AppData\Local\Temp ).
4 - clean out the sapinst_instdir (In my case C:\Program Files\sapinst_instdir )
5 - started the new SWPM and it worked.