Software can fail any time for milion different reasons that is why you should use Auto Save as Rick said but - and that was my problem last time. You have to remember that when you're using auto save - try to not use ctrl+s shortcut to often. Why? Because if you will use ctrl+s more often than you set auto save interval - you will have only one copy. AE is counting that time interval from last save so if you're saving manually (ctrl+s) auto save won't trigger.
Thnks Rick and Imeilfx, Autosave was indeed on. But because I'm used to using CRTL+S all the time the last auto save was made 6 hours before the crash. I looked there as soon as the crash happend when I realized no autosaves where made for a while. I figured it was the software failing, but I did not know about the 'skipped' autosave when a manual save is done. Was this always been the case?
It took me till 06:00 this morning to fix the presentation. Slept 1 hour during rendering and send it out 30 minutes before the first usage.
Indeed a hard lesson to learn.
Even better than relying on Autosave or the regular Save (Ctrl+S) is to use the command Increment And Save (Ctrl+Alt+Shift+S), which gives you multiple versions to go back to and can happen whenever you decide.
Todd is 100% right. I've learned that a hard way(3 hours work lost, 12 hours before a deadline). It's best to change all time habits when you are working in AE and:
1. set autosave to 20 copies, one every 5 minutes (that's my settings now).
2. hit yourself in the stomach everytime you wanna use CTRL+S more often than your autosave interval is set
3. Start to use Ctrl+Alt+Shift+S much more often.