As you said you can click OK and then proceed with Outlook (this is fine until you are able to use outlook normal).
Inorder to prevent this warning permanently, please follow these steps:
1. Click open Outlook. Go to File ---> Import and Export----> Select Export
2. Take the backup of every folder (eg: Inbox, Drafts, Sent Items, Contacts, Calender.. and so on)
3. Save the backup in your desired location.
4. Now go to Control Panel ---> Mail (Click on View by and select small icons)
5. In Mail Setup- Outlook ---> click on Show Profiles ---> select the current profile and click on Remove.
6. Click on Add and create a new profile .
7. After creating new profile import the backup into the profile.
8. Check whether you got everything and check whether its working fine.
Try this if it not works please let us know what the error is.
Thanks and Regards,