I'm going to say yes, though pretty fictionalised and nigh on impossible time travel is possible. Stopping time is impossible, unless you can freeze atoms, but time travel is highly possible. The idea occured to me randomly and I want to write a novel based around my idea, but I'd like to bounce the idea around a bit first and see what needs tweaking.
Anyhow, the idea will take a little bit of explaning, so I'll try and rail you onto my thought process (scary). If you throw a ball, you can aim it roughly and know where it's going to land but once it's left your hand you can do bugger all to alter it's path (we're going to forget about shooting it mid-air or things like that). Now if some being lets say god created the big bang, then every event is predeterminated, as if you strip away the complexities of life everything is just atoms bouncing around and for each bounce there's an effect.
Ok if you can get your head across my badly explained theses so far then I'll continue. So if atoms are always moving and if you could comphrehend enough you could see where each would go, I therefore reasoned that time travel could be possible in such a way. Highly unlikely of course, but what the heck.
My highly ficticous idea then would be to have a machine that could measure where each atom was, destroy them in the space outside the machine and think through at high speed calculating the paths of all these atoms before re-creating this scenario in the world outside. Those inside the machine will be safe and not destroyed, allowing for paradoxes and all sorts as time's still moving fowards the world has just been recreated differently.
Similarly for travelling back in time if you have this stupidly ficticious machine that could measure every single atom and it's path and then destroy and create it all, then it could track the reverse in flow and create it at a point where it wants. Hence time travel of a sorts, except time isn't travelled the world is just altered to a different point, but not a different point in time.
Ok I realise there's huge gaping holes in it, such as "that's a fucking stupid machine that wouldn't have the power supply to do those things nor the thinking process without being massive". A few little flaws I've been able to overcome in the land of comprhensive make-believe, was that if you wanted to travel back in time then the machine would save the world outside just before the person got into the pod, so it could retrace that persons atoms. Or some shit.
Wow, I'm going to give myself the convoluted bullshit prize 2008 for that idea. Still, there may be a little nugget of gold or at least hydroginated chicken in there.