It happens with the new version of the Portable Firefox. I think it doesn't manage to change the relative path or something like that. That's the error shown in Quicknote Tab:
// #5 File e:\PortableApps\Data\PortableFirefox\profile\chrome\quicknote1.txt is invalid or does not exist.
It seems the extension itself is hardcoding paths rather than using ones relative to the profile. So, that extension is not portable.
Sometimes, the impossible can become possible, if you're awesome!