Lightroom :: Upgraded 4.2 - Edit In External Now Loses History

Updated to LR 4.2, then when switching to 'edit in' Photoshop CS5 getting "This version of Lightroom may require photoshop camera raw plug-in version 7.2". However, checking for updates in Photoshop CS5 says all up to date as does LR. In the dialog I would say 'Open Anyway' and at some point I must have clicked the button to no longer show this message.
 
Now when I 'edit in' PS and come back to LR there is no entry in History, it's blank. In the past I would see one entry 'edited in PS' and then make further LR edits from there if needed. What happens now if I make an edit in LR I can't 'Reset' back to the original 'edited in PS' to start over because that doesn't exist in History. If I reset it will reset just above the last LR edit. This is awaful and has screwed up my workflow. It's damaged several PS -> LR edited images.
 
After LR 4.2 upgrade LR still showed an older version of RAW. Somewhere after I unchecked that box to stop the message, now when I look it says Camera Raw 7.2 even though I didn't do any further updates, and both LR and CS5 had reported they were up to date.
 
EDIT/UPDATE: I just found 'Reset all dialog boxes' in LR preferences and now I get the message again. It appears before I checked the box 'Don't show again' the last time I also clicked 'Render using Lightroom' rather than 'Open Anyway' which I was doing before that.
 
Now PS CS5 About -> Plug-in - Camera Raw is 6.7.0.339 and Lightroom 4.2 is Camera Raw 7.2 (?)
 
Windows 7 64 bit | LR 4.2 | PS CS5