Cannot back-up large pst-files

When I’m backing up my pst-file I get an error that tells me that there isn’t enough room on the external drive to back up the file. This cannot be correct; the file is listed as being only about 4.2 GB, and the external drive I’m trying to back it up to has over 31 GB of free space! Any clue as to what’s going on here?In which format is the file system of your external hard disk?
My guess is that you are using FAT32. In that case your maximum file size is 4GB. To overcome this limitation you’ll have to convert the file system to NTFS.

To do this open a Command window (for instance via Start-> Run; cmd) and type;
convert b: /fs:ntfs

Note 1: Replace b: with the drive letter of your external drive.

Note 2: On Windows Vista you’ll have to do this from an elevated command prompt. To do this press the Start button-> type; Command-> right click the Command application and choose Run as administrator-> confirm the warning message and/or supply administrator credentials if requested.

Note 3: To see the current file system format, right click the drive in Explorer and choose Properties.

Note 4: There is no way to convert the file system back to FAT32 without formatting the entire disk.

Note 5: Windows 95, Windows 98 and Windows ME cannot read NTFS formatted disks. Windows NT4, Windows 2000, Windows XP, Windows Vista and any Windows Server product have no issues with it.