On each occasion when this has happened it has only been myself, so the team with me had not been affected. Usually when a large mob surrounds you and when pressing the Stim button your life is not affected, as if it had frozen somehow and then find you are lying on the floor.

This seems to happen randomly I doubt this would only happen in certain area's, that said I can try and work out the area's from the Maps posted with the Screen shots and get back to you

Iv'e been around since the First days of SL closed 'Beta' and have not come across this in any other map except Shipyards. Most players have just taken this one on the chin, so will spread the word to the original poster's to note if they remember where this happened exactly and on what map or when this occurs again to do the same.