ACRORD32.EXE executable file has been changed, is it safe?

I have KIS 7.0 and my firewall warning came up that ACRORD32.EXE executable file had been changed since last scan. I was looking at a pdf of a water park brochure and it came up and it also comes up when I try to update Adobe reader. I know this is a adobe reader exe I am just wondering if everything is safe to allow through my firewall. I was also wondering if me having my KIS firewall on training mode is why this is happening and should I go to low security mode. Any help would be greatly appreciated.