User could not print from any applications that opened after double-clicking the attachment from an Outlook email. This is in Citrix using published applications. I was able to print the attachments if I was in a published desktop. The user would get the message "Identity Switch Canceled: The current identity could not be chagned because one of the applications was unable to switch" whenever he first opens Outlook.
I researched and found an article in Microsoft which was very confusing and from a forum which didn't help as much either.
I ended up logging in as administrator and opening regedit. I compared the user's Identity registry settings with another's under HKEY_USERS. Made the appropriate changes...adding User ID key, changing "Last User ID" key to match the Identity string...changed the Last Username to "Main Identity"...etc.