One time backup of my system drive has failed: This op. cannot be perf. while Win runs

Hey, thanx for the fast reply!

Okay, I checked that. I set the page file to drive D: instead of drive C: what I wanna back up. I also checked the destination drive. It has more than 110Gbytes of free space. The problem and the message has not changed.

What else can I do for better result? I can say again: the system backup is working on two different machines but not working on the third one