I had a very similar situation. Actually called Southwest in a panic (crazy, I know, but I REALLY love Ding!!) (I kept getting the little icon on my desktop with the exclamation on it)
Anyway, after walking thru the download with them and then doing the same thing with my service provider, both of which did NOT work. My service provider had me reboot the computer, shut off my NORTON (until you restart) and re-load DING, then restart the computer. It is very likely that your antivirus was re-configured during whatever change you made and now your security does not recognize it. I did that exactly and it worked!!
I was thrilled after having lost Ding for several weeks and getting NO WHERE fast,
GOOD LUCK, I hope it works!!