recently we have noticed a very wierd error and it is actually very bad for us!

We use "events" to create our services to be delivered. All services have a start date and an end date ... until about 1 week ago everything was perfect and suddenly all "end dates" of our events show 1 day later. Even though when I open the event to modify the date, the date is correct in the modify window but shows 1 day later on the activity main window. I am attaching 2 screenshots 

VERY URGENT!!

Thank you very much in advance