320GB seagate freeagent, cant open some of the files.

If you have the ability and space then recover any files that you can

use the RUN option from the start menu

now type in "cmd" then ENTER

Now in the black box that appears type "chkdsk x: /f /r" and press ENTER

The "x" is the drive letter of the drive you wish to check

It may take some time but this will try fix any errors it comes acrosss and you may have to re-start to complete the task.

Now remove any more files that you can.

Use the RUN command again but this time type "compmgmt.msc"

Select Disk management

Make sure you freeagent is listed here.

Right click and select "Format"

Select NTFS as the file system

Do not tic any other boxes

Click OK

When it is done you can move the files back to this drive.

It is quite possible you hit the limits of the FAT32 file system which would have caused the types of error you saw.

Harddisk could have been damaged. Have it replaced if you still have warranty on it. Otherwise try to run good harddisk repair tool like Norton Disk Doctor. Boot the computer from CD run Harddisk diagnostic program and see whether it pass the test. The diagnostics program are usually available from the website of the manufacturers. Another way the problem could be solved by running the scandisk to check physical damage of the harddisk. From windows you can do the same thing using the Error checking from the harddisk drive's property's options in my computer window.