Issue when syncing iPhone to iTunes when adding movies I'm having some trouble with my wife's iPhone (4 running ios5.1.1).

First what works

If I plug it into iTunes (10.6.3) it will sync happily, backup happily and appear to work.
I can also change without issue the photos and apps that are sync'd.

Then what doesn't

If I try and change the movies (or music) that are sync'd (currently none are) then when I click apply the following message is shown. 
"The iPhone “XXX’s iPhone” is synced with another iTunes library. Do you want to erase this iPhone and sync with this iTunes library?"

With options of Cancel or Erase and sync

I've tried following the instructions here:
https://discussions.apple.com/docs/DOC-3141

But that doesn't appear to have resolved the issue.
I would like to be able to add movies or music without losing the existing content (state of apps etc.)
OK so after talking to Apple support last night:
The messages only apply to the "tab" that they show in. So in this case clicking erase and sync wasn't an issue.

Ben