Angel13, install patches 1.4 and 1.5 and start the mission again through the campaign menu. Version 1.5 is the most reliable. 1.6 is buggy. I don't know about the bugs in version 1.0, as I haven't played versions lower than 1.3. I think that version 1.0 has a lot of bugs. Although, people have completed all the campaigns even with this version.
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