It sounds like you might have a corrupt disk, to fix the problem you need to right click on the drive in my computer, select properties then tools, click on the button check the disk for errors and select the two checkboxes before hitting start
it will most-likely ask to 'dismount' the volume, its your choice but it means lock it out so nothing else can open or modify any files during the check, it will return to normal once it has finished, i recommend hitting yes
if it asks that it cannot complete the disk check at the moment or something, do you want to check the disk at boot up, select yes and will check the disk when you next boot windows
if this does not solve the problem email me back at ant_coe_Email Removed, it would be great to find out if the file system on that drive is fat32 or ntfs.
best of luck
Tony