Who knows! You need to give us some more info. Exactly what were you doing at the time (what exactly do you mean by "open pictures")? Was it behaving itself before, or is this a brand new install? What version are you on?
And by the way, this is a user-to-user forum. We're not Magix staff and we have no control over the program.
As @AAProds has commented we need more information - see this topic for what is required and please quote processor and graphics card make/model in full, and also what monitor/screen resolution(s) your are working with if this is a laptop.
I would suggest you put this information in your profile signature so we do not have to keep asking for it.
Are the graphics card drivers up to date?
A screen shot of the Program settings, Display options or Device options tab would help.
The amount of free space on the hard drive(s) you have.
Was there any error dialog that popped up when the crash occurred, if so what was the message? If not then to determine what the cause of the crash was see, this short tutorial on using the Windows Reliability Monitor.