crackle when recording instruments

Hi

im new to pro tools but ive got a few friends who have been using is for a while.

when i record any audio from either my keyboard plugged into a usb or a guitar straight into the DI it starts to crackle.

i thought at first it must be my guitar cable but it also does it with the usb powered keyboard too :mad:

any thoughts as to the cause of this?

also, when using the guitar through the amplitube plug in its very noisy. i tried turning us the gate and that killed it while i wasnt playing but as soon as i played the guitar there is a lot of fuzzy noise. strangely if i put my hand on the top of the M-box it stops the fuzzy noise but i cant keep a hand ontop of the mbox and play guitar. could this be something to do with the earth (ground)?

any help appreciated



im using pro tools 9 on a sony Vaio laptop with an m box mini and an m-audio oxygen49 keyboard.

cheers