Error trying to track email with attachment

I have a user getting this message randomly when try to track an email in Outlook CRM 2011:

An error occurred while promoting a Microsoft CRM e-mail message.  Restart Microsoft Outlook and try again. HR=0x80131501. Context=. Function=CMailItemHelper::HrPromoteMailItemInCrm. Line=1783.

I have given the user Sys Admin role to rule out permissions. Same error occurs.

I have increased the default size of an attachment from 5mb to 32mb. Still same error.

Any Ideas?