A laptop question

As of sometime yesterday my laptop will no longer stand by or hibernate.

If I close the lid, try manually via the start menu or leave it until it should hibernate on its own, it begins the process then I get a screen saying stand by in progress (or something) and the whole thing jams up, meaning that I have to turn it off and on again.

Now my laptop doesn't like this. Because it hasn't been 'closed down' properly it won't start up properly. I spent almost three hours last night just trying to get it running again.

As my laptop is now my ONLY way of accessing the intertubes, it's very, very important that I keep it running.

It's running XP.

Any ideas on how to make the stand by facility work again?