Thanks for replying Ivan!
Actually I was working with some weird shitty audio files recorded with a mobile phone. The extension is 3gp and the frequency 8000Hz! That may have been the problem. However they have been in the timeline for one week and it was working fine until a couple of days ago when it started doing some strange things, like taking a few seconds to do simple things like trimming.
Regarding the video files I´m mostly working with the native files recorded with the 5D. But there some other video files in the timeline with different formats, codecs, frame rates… Could that be an issue with the CS5?
I opened the oldest autosaved version but I have the same problem. I can open the project but not the sequence in that project. Any solution?
If I open the project with the CS6 you think that could fix the problem? I have to recover this sequence!
Thanks again mate.
Juan