I wish people would look this thread up first before making their own thread asking for help, this thread should cover your issues, if not then you should really say something about it not working when making the thread
I had the same issue (got me in alot of trouble with the PLPD), you can simply unsubscribe from the prone mod or if that still doesn't work you may unsubscribe from HL2:RP content if you have any as Civil Protection SWEPS seemed to also give me that error. Hope this helps.