NTFS File structure corruption

I am trying to solve a problem reported by my user. Recently he transferred a huge amount of data from portable harddisk to local G drive. G drive is a Maxtor 250GB harddisk with single partition. He restarted his pc and when booting up, juz before entering the windows 2000 login screen while still in dos, the pc started to delete all files from the G drive. After logging in, all the files are gone. The event viewer shows that there is corruption in the NTFS file system structure.

Does anyone know what went wrong? Is it caused by virus? Because i need to give a report to my user explaining the possible cause.

most likey what has happened is the MFT (Master File Table) has become corrupted. Since small files are stored in this, some file loss has already occurred. The files are not really gone from the hard drive. In most cases they are just missing from the MFT, so Windows will not see them. First before loading Windows again or changing anything, make an image of the disk. Then run the following on the drive:Depending on the drive size, this could take some time, this should correct the MFT table. If it doesn't or gives an error, please post the error. Its important that you do an image of the disk before doing this, otherwise more data will be lost. As for possible causes, could be anything: from cosmic rays to changes in Earth movement, to a hard drive malfunction. Who knows?

Hi, i have not tried the chkdsk utility, but i dont think the files are still available because not just the files are not found, the disk space has been freed also. I run some recovery tools on the machine but cant recover muuch either.