It may be possible to fix the problem using these steps :

Open Outlook Express

Click "Local Folders" in the left side navigation

Select New Folder and name it TEMP

If possible move all of the email from your Inbox to the TEMP folder

Go to menu bar and select Tools - Options - Maintenance - Store Folder

then write down the location of your inbox

Close Outlook Express

Use My Computer to go to the location is step 5 and then delete the file
inbox.dbx

Open Outlook Express - The Inbox folder should be auto recreated

Move your email from the TEMP folder back to your Inbox