ahnilated :
I don't know why you would get an error to run chkdsk in Windows. Linux has commands to check a drive for errors as well as programs that will do that. Did Chkdsk find/report any problems?
The external was formatted as ntfs and I understand Linux ubuntu either does not or does not recommend checking disks formatted in that way. (edit: I should say that I checked the file system with disk analyzer on ubuntu and it said to go to windows ....) Anyway, it has happened also on another external I have; not certain if that one is ntfs also or FAT - same error message received when checking the file system with instructions to attach to a Windows pc and run "chkdsk /f".
If I recall, it said errors were found and fixed. But then, nothing on the drive when it was checked.