Hi there and welcome Norman
Can you tell me the version of windows or mac you are using please?
I want you please to do a system restore to undo any corruption that can cause this
To do this, close all programs.
Click start, system restore.
Then follow the onscreen steps and perform a restore choosing a restore date before the problem start.
Let this complete and tell me if it now functions correctly.
I can also do these steps for you, and have made a request via Additional Services. This is optional, and if you choose to do this, I can, with your permission, remote into your computer while you watch and do all these steps (and deal with any problems that arise during them) for you. Or if you do not choose to take this service, we can continue here. This is no problem at all. Just let me know please.
Else let me know the results please.