Problem when syncing profiles of TP and TBP (both with GPG/Enigmail)

On my desktop PC I use Thunderbird (with GPG/Enigmail), when I'm out I'm using Thunderbird Portable (with GPG/Enigmail) on my USB hard drive.

To have all my mails on both installations, I tried to sync the profile folder of TP

C:\Documents and Settings\dhoughal\Application Data\Thunderbird\profiles\xyz

to TBP's profile folder

F:\Program Files\ThunderbirdPortable\Data\profile

That worked fine. But when syncing TBP's profile folder back to TB's profile folder and starting my local installation of TB, I get problems with Enigmail, as TBP has reset the GPG executable path in prefs.js to

F:\Program Files\ThunderbirdPortable\app\gpg\gpg.exe

TBP seems to have a function (maybe in its launcher) to reset the GPG executable path.

Any ideas how to reset the path after syncing the profile back to my local TB installation?

Cheers
D.