My prefs.js file has the following setting for enigmail:
user_pref("extensions.enigmail.agentPath", "S:\\software\\Portable Thunderbird 1.5rc1 with gpg and enigmail\\PortableThunderbird\\gpg\\gpg.exe");
If I change my drive letter for the USB device, the NSI code doesn't update this field. I am unable to send encrypted email or do key management.
I've also tried all manner of "..\\gpg\\gpg.exe", etc, without success.