Start the laptop with a clean boot and then check if the copying function works OK.
If it does then perhaps a 3rd party program may be the cause of the problem. The link above explains how to find it if it doesn't happen when using the laptop this way.
I am leaving my comfort zone of Macs here, so bear with me. Do you have any antivirus that could be scanning files and slowing down/stopping the process?
1 
Hi @brido
Start the laptop with a clean boot and then check if the copying function works OK.
If it does then perhaps a 3rd party program may be the cause of the problem. The link above explains how to find it if it doesn't happen when using the laptop this way.
jayeff さんによる
Sorry but it didn't still work
Brido さんによる
Hey Mate,
I am leaving my comfort zone of Macs here, so bear with me. Do you have any antivirus that could be scanning files and slowing down/stopping the process?
Falcon 16 さんによる
I dont have any antivirus
Brido さんによる
Do you have any 'safety' applications running? Also, when this occurs next, might you be able to send me the memory dump so I can look through it?
Falcon 16 さんによる