Toshiba Satellite M60 problem.

Hello. I've browsed these forums before after needing help, but this is my first post. As you will be able to tell, I'm not that technically minded, so forgive me please if this question seems obvious to you. I'd sure appreciate any help.

I have a Toshiba Satellite M60 which is just over 2 years old. I've noticed recently that the battery life was getting very poor; it was running at little under 30 minutes if I was watching a DVD, for example.

Last week, the laptop would not turn on. It tried to get started, but then just cut out before powering up. I tried a few things, including taking the battery out, putting it back in and then starting again, and it then did start just fine. However, it would only start with the mains electricity not connected; only on battery alone. I am still starting the laptop like this, and the problem is still the same. To start my laptop, I have to remove my battery, put it back in, start up, and then when it has powered up, I put the mains power in. If I do this before, it won't start.

Do you think this is likely to be just the battery that needs replacing, or is the problem more severe? I am no longer under guarantee, so don't want to pay for a service if a replacement battery would solve the problem, but similarly I don't want to pay for a battery only to find that doesn't work, and the have to pay for a service as well.

I hope you can help. It will be much appreciated.