Hi
Sorry, I've never seen "render the video destroyed" message. At what point does this message appear?
Clip preview will just preview the clip you have selected, so seeing the whole clip in this window is normal. Sequence preview should play the whole timeline.
I suggest you go into options and set up dual displays. You may then be able to pinpoint which clips don't play
Place cursor on a particular clip and click that clip on the timeline. It will now show in both displays. Play the Clip preview screen. Both previews should then play together up to the end of the selected clip.
How many tracks are you using?
Using Save Project As regularly, giving an incremental name each time should allow you to return to the last working edited version in which case you will lose little in the event of problem. As Borate says you need to share the project when someone can take a look and check it out. Most people find the application quite OK. Bugs do occur as with any complex software but are quickly sorted out or a reason found.
Nat