Moving Mp3gain Portable is not recommended

Hi,

I installed MP3GainPortable_1.2.5.paf.exe in folder A on my laptop, so a folder named MP3GainPortable was created in folder A. I ran MP3GainPortable.exe from that folder and it worked fine.
Then I decided to move folder MP3GainPortable to folder B (still on the same computer), and when I run MP3GainPortable.exe a message pops up which basically reads: "The MP3gain Portable path has changed from A to B since it was last launched. Moving portable applications is not recommended since some features could stop working. Do you want to continue?"
[That is not the original message, I translated it into English.]

Then I click "Yes" and MP3Gain seems to work fine, but surely their must be something wrong if a portable app cannot be moved to a different folder... Moreover MP3gain Portable seems to leave many keys in the registry (or is that normal?).

Could somebody please investigate this problem?

Cheers