Why all the errors appear after some hours on pc
Hi,
On this case i recommend trying to run a diagnostic on the drive to see if it does not have any errors. Here is a link to a software that might help diagnose the drive:
http://support.wdc.com/product/download.asp?groupid=613&lang=en
The software is Data Lifeguard Diagnostics, you have the option to use it on DOS or Windows.