The only thing that can be said with certainty is that Windows told calibre that Windows failed to read data from or write data to the hard disk, in this case calibre's database. From there it is guesswork.
Usually such problems indicate that hardware is failing. It could be that some component is getting too hot to work properly, that memory is failing, that the disk itself is failing, or a number of other things. Sometimes, but much more rare, the problems could caused by damage to Windows itself. It is even possible that the problem is caused by some other program on the system that is connected into the guts of Windows, for example an antivirus or synchronizer. Unfortunately, it is impossible to tell which of these might be the culprit, or whether it is something else.
Sorry that I can't help more.
