Why does MacBook Pro quit open applications, rather than sleep with Cinema Screen connected?

Question

With my  Apple Cinema Screen connected, my MacBook Pro has recently started getting into a muddle with the sleep command. 
The problem is apparent when awaking from sleep mode.  Sometimes, only some of the open apps have been quit (Safari, Calendar, Word etc). At other times, all the open apps and the whole user account has been closed. On those occasions, re-opening the user account becomes a lengthy process, often requiring the user's name and password to be entered twice, (with two different non standrad wallpaper backgrounds)  before restoring everything to the condition prevailing before sleep was invoked.
Interestingly, the MacBook Pro works perfectly if used without the Cinema Screen attached. It fires up and sleeps and reawakes with everything in tact, as it should.
Disconnecting the cinema screenwhile the MacBook Pro is asleep creates the above scenario upon awakening.
Similarly, if the MacBook Pro has been used without the cinema screen, is put to sleep and while asleep, the cinema screen connected, the above symptoms plaque the re-awakening process as described above.
I think but am not 100% sure, that these probelms after the recent Mountian Lion update was applied (OS X 10.8.3).
Genius Bar folk (Harlequin Centre - Watford) have not heard of the issue.
Can anyone help please?
Thank you in anticipation of a solution from a bright spark somewhere!

Answer 1

The next time you have the problem, note the exact time: hour, minute, second.
If you have more than one user account, these instructions must be carried out as an administrator.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Console in the icon grid.
Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select
View ▹ Show Log List
from the menu bar.
Scroll back in the log to the time you noted above. Select any messages timestamped from then until the end of the episode. Copy them to the Clipboard (command-C). Paste into a reply to this message (command-V).
When posting a log extract, be selective. In most cases, a few dozen lines are more than enough.
Please do not indiscriminately dump thousands of lines from the log into this discussion.
Important: Some private information, such as your name, may appear in the log. Anonymize before posting.