Using IOS 6, why does it keep adding an unwanted alert?

I have deleted all entries of this particular event and then re entered it as new and a week later it did it again! It starts adding an alert the day before at 9am. Not to all entries, it just seems as if it is this particular set, or if I try to delete and replace. Crazy, I know. It should not know the difference between events but somehow it does! No one else has access to my calendar but me and I am only using ICal. I am stumped. I must be doing something stupid or this program is seriously possessed. :-)