Why did the Python copy script start to crash?

Question

Python

Hello!
There is a Python script that has been working properly for a long time. The script is simple, copies video files using shutil.copy("what", "where") from one hard drive to another. Files are 8-10GB in size. Until yesterday, I copied, and today it began to fly out with a Permission denied error in a random period of file copying. Some files are copied.

OS Windows 7. The rights to the folder are full. Disabled antivirus, firewall, ran as administrator - did not help. Climbed into the debugger - gives the following

I can not understand what the problem is.

Answer 1

The problem was in the new HDD with bads

Answer 2

What's in the length variable before the flight?