Calendar Events Rearrange Themselves – Microsoft Office for Mac 2011

Office for Mac 2011 has been acting up for about half a year. The first time I noticed something off was when I try to categorize an event under a certain category and the event deletes itself after a few seconds of saving it. If I change the color, the title, or make a completely new identical category its the same problem. If I make the event first before adding the category, it deletes itself once it is placed in that category.

The second problem is now some events are moving to a different date on their own. These are random occurrences but they're mainly events that are occurring within the next few days. Nothing else is changed, it's just as if it was dragged into a different date. I don't believe it has anything to do with restarting the program, sometimes I just come back to it and it has changed. This occurs less frequently but has happened about 3 times so far.

Let me know if either of these problems can be fixed. Thanks.