You can open PowerPoint or any other Microsoft Office family program easily by pressing CTRL key while the program is starting. This will open powerpoint in safe mode and can be used to track down problems with your current installation.
Alternatively you can use the command line parameter /safe while starting powerpoint or any other Office program from command line interface.
Microsoft Office Safe Mode allows you to use powerpoint that has encountered certain startup problems or problems related to addins that were not installed well or failing at certain point. When a problem is detected at startup, Office either fixes the problem or isolates it, allowing the program to start successfully. However, you should be aware that safe mode has some restrictions.