Disk checking is meant for checking your disk for any types of problems or errors or its state.
If your disk have some file indexing made wrong, or if HDD have some bad sector in some part, Security features or type of disk partition have been modified by some unwanted program or malicious user, then in that case, system automatically sets disk check whenever the system restarts again.
And if you want to avoid those things, allow disk check to check your all disk once, and probably the same thing would never happen again in your PC until some other problem pertaining to system or making harm to system not occurs.
DiskCheck is the best thing provided by the OS. Otherwise many of the users might have suffer from Security problem, or might they get little time to backup their all important files(in case of bad sector in HDD). Because bad sector is one thing that makes your HDD behave as if there is some hole. When you put data there it gets save temporarily. But when you try to access it again the same data is not there. It is blank there or missing there.
Hope all it helps you to understand.
Vikram Singh Saini
RESULTS MATTER, REASONS NOT!