hello, could you provide your latest few submitted crash reports? please enter about:crashes into the location bar, copy the latest few report ids from there starting with bp- & paste them here into a forum reply. this will give us a better understanding what may be triggering those crashes.

Philipp, As you requested, I listed below all of the crash reports. For some reason I don't see the most recent ones as of 1 crash today, 1 crash yesterday and on... bp-04f34545-d75f-495e-a27a-3e8ed2150508 5/8/2015 9:53 AM bp-8947e1a5-0767-4222-97b5-1821b2150508 5/8/2015 9:42 AM 94ef49ac-68e3-4aed-8044-0d61fb009eea 5/6/2015 10:48 AM cce0a27a-6e54-457d-bb40-a989faa3312d 5/6/2015 6:43 AM 3bbaa91b-cbab-408f-9398-92041ec58e4f 5/6/2015 6:43 AM c06c55d2-6662-42b4-8661-79e06e6a28be 5/5/2015 5:54 PM 1c4f20d5-3d0f-4885-84c3-8c6a8ddd20f5 5/5/2015 5:54 PM 6b8a1b0d-fb3a-4738-9450-080a87ecdca3 5/3/2015 12:33 AM 3d0de3eb-28ce-43d8-8def-34d18f3059fd 5/1/2015 8:09 AM 98df8ed5-911f-4699-bcb8-5b5ec9ec466b 4/29/2015 4:32 AM 49c15eba-d55d-4452-b316-ffeb4cf0e7d9 4/25/2015 6:49 PM 085770b0-554f-4913-87ee-e581222d2e97 4/13/2015 1:54 PM 13083991-699c-4452-b1d5-ab35a25dcb51 3/3/2015 3:36 PM

thanks, but unfortunately those are all a few months old and won't relate to the current situation. could you try to refresh firefox and see if this will address the issue...

some other generic tips to troubleshoot crashes can be found in this article: Troubleshoot Firefox crashes (closing or quitting unexpectedly)