Ok guys,

I know that you all receive a lot of posts like this, but I'm really down right know. I'm heading into my 4th year of my PhD program, and I'm starting a brand new research project. We work in a system that is very interesting and can be wondrous, but can also be unforgiving. I'm starting my 3rd project, the others has failed for different reasons. The current project is based on the work of another grad student in the lab who has had wonderful success with her end. I was getting ready to go to field for a week long research trip when my advisor had a surprise meeting with me here he basically broke down my spirit. Right now, I feel like the lowest person in the world right now.

Are you based in the UK? If so, I am a bit concerned that you have to start a new project in your fourth year. I understand that lab work can be fickle, and in the end you need enough material for a thesis, but do you need to start this new project, can you not build on what you have found (even if it's negative results) in previous work?
How does the research trip fit in? You have not expained that bit enough..
All I can think of is: Don't give up! If you have concerns about the new project, talk to your supervisor about it and suggest some other ideas that you prefer doing. I know impromptu meetings can completely throw one, but after some consideration (and recovering), arrange a meeting with your sup and see whether you can take matters further in a positive spirit.
It can get tough at times, but dont give up!