[quote="mrgorilla"]--snip-- When I plug the guitar in, that is when the humm shows up. HOwever, when I touch my computer or the MOTU or the ends of the input jacks, then the noise goes away.[/quote]
This definitely sounds like an 'earth' problem - improper grounding somewhere somewhere
If it is a low hum it is likely to be a groundloop - some devices will have an 'earth lift' that often solves the problem. Try to make sure that all your gear runs off the same power circuit, this often helps.
It may also be improper shielding on the guitar, touching the MOTU does it change when you touch and release the strings whilst not touching anything else?Try this in an amp as well.
Check on the net for further info on groundloops and hum,
KMI StringPort_1650, SoftStep_VK2 v1.2 & MIDI Expander; Mac_Moore Guitar,
Roland VG 8, 88 & 99, YamahaVL 70m; OSX 10.6.8, iMac i7 2.8G QC; MaxMSP 5.1.8, Ableton Live 8.2.2, M4L, SC3, QC, cSound, etc, etc,