Facing problem with Outlook 2003 when accessed by .Net application

We have recently migrated application from VB6.0 to VB.Net. Application accesses the mails from Outlook 2003 and displays in the application for reading the attachments or body text.

But after migration we are facing problems with the Outlook shared email account (while the application is running):

1) When manually mails are moved from first folder to second folder in Outlook, another user is still able to see the mails in the first folder and when the second user tries to move the mail manually, he receives an error "Can't move the items. The item could not be moved. It was either already moved or deleted, or access was denied".
2) The unread mails count shown in Outlook is not reflecting immediately for other account users.

Can anyone please help in resolving the above issues?