Hi Vince,

In order to assist with email attachment issue we would like to have more information

1.  What is the Operating System you use?
2.  What is the version of MSN Software?
3.  How long it’s been that your are unable to view attachment in MSN?
4.  Do you get any error message? If so provide us the detail description
5.  Where there any changes made on your computer?
6. Provide you impacted email address?

Things to try:

Please check if you are able to view the email attachment in the hotmail website http://www.hotmail.com and does it also takes a long time to view it.

If you are able to view the email attachments in the hotmail without any problem then it is an issue with MSN software as it is not getting synchronize with your account you need to rename the.sdf and check .
Please find the below steps to rename the .sdf files.

Windows Vista/Windows 7

Note: Sign out from MSN then close the program before performing the steps below.
            1. Click ‘Start’
            2. In the Search box, type the following: %USERPROFILE%\AppData\Local\Microsoft\MSN
            3. Press the ENTER key. The MSN folder will open.
            4. In the MSN folder, do the following:                       
                a. Click ‘Organize’, ‘Folder and Search options’, then ‘View’
                b. Put a dot on ‘Show hidden files and folders’
                c. Uncheck the ‘Hide extensions for known file types’ and ‘Hide protected operating system files options’
                d. Click ‘Apply’, then ‘OK’
         The db30 folder will appear inside the MSN folder.
          5. Open the db30 folder then look for files that end as msn-com.sdf and msn-com_JMF.sdf
          6. Right-click, choose ‘Rename’ and add .old after .sdf to both these files
          7. Close the db30 folder

Windows XP

Note: Sign out from MSN then close the program before performing the steps below.
 
         1. Click ‘Start’ then ‘Run’
         2. Type in the box: %USERPROFILE%\Local Settings\Application Data\Microsoft\MSN
         3. Click ‘OK’ The MSN folder will open.
         4. In the MSN folder, do the following:                       
                   a. Click ‘Tools’, ‘Folder options’, then ‘View’
                   b. Put a dot on ‘Show hidden files and folders’
                   c. Uncheck the ‘Hide extensions for known file types’
                   d. Click ‘Apply’, then ‘OK’
         The db30 folder will appear inside the MSN folder.
         5. Open the db30 folder and look for a file that ends as msn-com.sdf and msn-com_JMF.sdf
         6. Right-click, choose ‘Rename’ and add .old after .sdf to both these files
         7. Close the db30 folder

Please revert back for further assistance.
Thanks!