input / output error when copying large file

I'm trying to copy a large data file (MAILSTEWARD DATABASE) to another drive.

Repeatedly I get about 90% of the way done, but then it stops on me, I get the message that there's an "input / output" error.

I need to copy that file off so I can erase and repartition the drive that it's currently on.

When I open up the program MAILSTEWARD, it doesn't seem to have any problems - I can access all the data in the file - but I just can't copy it.

Going to check with the makers of the APP, but does anyone here have any suggestions?

Thanks!

Will