I don't what's the exact problem there, but still you may try one of these:
- Run ScanDisk in MS DOS Mode.
*Click on Start >Shutdown >Restart your system in MS Dos Mode.
*When your system will be started in DOS, type Scandisk to run it.
*When it's completed, then type Win to restart Windows.
If this doesn't work, then try the second one.
- Start Outlook Express > click on File > Compact > Compact All.
Try both one by one. Good luck.