No sound or strange sounds when trying to record guitar

Hi!

I'm new to Logic Pro, after having worked with garageband for many years. I've just been trying to record guitar through my audio interface, with strange results. I've set my audio in and output source as my M-Audio firewire solo, created an audio track, and selected the guitar sound I want. At first there was no input, then when I deleted the first track and created a new one, I could hear the guitar through the monitor and it was being input, but it had a horrible distorted and out of tune sound - and that was how it sounded when I recorded it too. Then I tried it again and it seemed to be working fine for about 5 minutes - it sounded fine through the headphones and the recording was right - but then went back to the strange sounds again - without me changing anything!

I'm using Logic Pro 9.1.8, on a Macbook Pro running Mac OSX 10.8.3, and have a M-Audio Firewire Solo audio interface.

I'm very frustrated right now - so I'd be grateful for any help!

Thanks,

Stephen