Defragmentation error with GCFScape Team Fortress 2
During defragment the data in hard disk is sorted in proper way and empty space between data is removed so that operating system can easily allot space to new data and head of the hard disk takes less time to get empty space. It is helpful in increasing life time of hard disk. This problem could because of software error or hard disk damaged sector.
If you restart the defragment and operating system does not show error then do not worry this error was due to pointer indexing and now sorted by software. In other case if this error is again and again raised its mean there is sector in your hard disk which is damaged physically. You need to repair you hard disk or replace if there are many bad sectors.