Unable to open Windows LiveMail stored on my computer

I recently transferred all of "My Documents" to my new Windows 7 computer. This folder contained many of my IMPORTANT Outlook Express saved emails. These emails now appear as Windows Live Mail. In order to now open these email files I downloaded Windows Essentials as instructed. For a day or 2 everything is fine, and these emails can be opened. Then I get the message that Windows is unable to open them. I subsequently remove Windows Essentials and re-download it again. This process has been repeating itself for over a week and I have no idea why. Being less than computer savvy it is very frustrating! Any assistance you can provide correcting this repeating problem is appreciated.