windows mails problem

I have created many folders in my inbox. I regularly take back-up of my mails in external hard disk. Recently I had to do system recover due to virus problem and lost all my mails. I imported mails from my external hard disk along with all the folders intact.

Since yesterday I am facing a weird problem. 2 of my folders are acting funnily. If I click any mail in one folder, I see same matter for all the mails although I can see different subjects for each mail.

For other folder if I click any mail I see following message -

Message could not be displayed
Windows Mail encountered an unexpected problem while displaying this message. Check your computer for low memory or low disk space and try again.

Can anyone guide how to sort out these 2 problems ?