I still have Win XP SP3 and use Firefox as my browser which is still compatible. I also have I.E.8 which I don't use as out of date and do not have Chrome installed. I upgraded from Firefox 50.1.0 to 51.0.1 today and noticed that after installation the hourglass continued to show beside my cursor as if it was still busy. I opened the task manager to see what was going on and every single process had changed to conathst.exe (from memory I hope I've remembered it right) which I find is a Norton process. I closed Firefox 51.0.1 and started it again. This time my task manager showed all the processes that I am used to and I assumed all was correct for a moment but as i watched each and every process changed to conathst.exe again so I had a great list of conathst.exe and nothing else. I have rectified things now by restoring my computer back to Firefox 50.1.0 but I am concerned as to what is going on.