1) The easy way (easy for me: one line of explanation

) is to hard-reset your PPC.
2) The information MS Reader uses is stored in the following files stored in the Windows directory on your PPC. Back them up on your PC so you can return to where you are today if things go wrong.
Microsoft Activation.Unload
Secrep.dat
Secrep.dll
Secrep.xml
Secrepid.dat
I think this will work: After backing them up, erase the files. Soft reset the machine. Run Reader. You should now have the ROM version of the files.
When you have activated the PPC, back-up the activation (burn them to a CD) so you in case of a hard-reset can "re-activate" without bothing Microsoft.
To reactivate the backed-up files:
1. Soft reset Pocket-PC to ensure no programs are running
2. Use Windows Explorer on your PC to copy (and overwrite) the above files into the \windows directory on the Pocket PC
3. Soft reset the Pocket PC again
4. Find \Windows\Secrep.xml with File Explorer. Double tap the file.
5. Run MS Reader: it should say that it is activated in your name
Jorgen