i've been struggling with this for a while now: i can't install greasemonkey on my firefox portable 3.5.5 :( it must be something with the latest update to 3.5.5. (i'm having win7 x64 ultimate)
upgrading greasemonkey didn't work so i completely de-installed it and then tried (no success):
- installing greasemonkey via addons-dialog
- installing .xpi manually
- installing with "restart firefox" button
- installing by quitting + restarting firefox
it simply just won't install / show up under addons. of course i de-activated all other plugins and started firefox as administrator.