You may want to run the McAfee Virtual technician founs at the top of this page under Useful Links in the Technical Support area. MVT will scan your computer for any McAfee related issues and attempt to fix them. When MVT is finished you could try to contact Technical Support Chat which is free to use and they are available 24/7 for further assistance regarding your issue.
Ok I do not have outlook to test but does this "fix" help?Check where extend.dat is aiming
When people migrate their data they may bring a file from a 32 bit system to a 64 bit system. The problem is from the 32 bit system McAfee will have installed all of its files under the c:\Program Files\ folder. Which it should because it is a 32 bit system and only has one Program Files folder structure. When you migrate to a 64 bit system you have 2 Program Files folder structures.Open Extend.DAT in the C:\Users\%USERNAME%\AppData\Local\Microsoft\Outlook folder structure it might still hold the previous information for the location of the MSK folder structure on the old 32 bit system. So I renamed the extend.dat file to extend.old and reopened Outlook and it created the new extend.dat file pointing to the c:\Program Files (x86)\ folder structure.
Check also Web and email protection/antispam/email processing that the place in antispam folder is ticked.