Here's the answer of Aspyr Technical Support, they confirm this issue happens only with pre patch games loaded after patch:
Ticket #23554: GUI disables after Leader contacts in Civ V G&K v1.0.1.994 (1...
Your request (#23554) has been updated.
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http://support.aspyr.com/tickets/23554
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Aspyr Technical Support, Jul 10 04:34 pm (CDT):
Thank you for providing us with the requested information. This issue has been logged with our developers to be resolved in an upcoming update and only occurs with save games started before yesterday's update. At this time, we can only recommend starting a new game to bypass the error.
Thank you.
Aspyr Support
alfa666, Jul 10 12:49 pm (CDT):
Here are the files requested. The autosave shows the exact moment the issue
happens, on the regular save you have to play one or two turns for an AI to
contact you.
Thanks for your help.
Attachment(s)
0ldAutoSave_0173 AD-1130.Civ5Save
MacBook Pro.spx
Dido_0172 AD-1120.Civ5Save