Hi, I've plugged my bass guitar into my computer via the microphone port (noobish i know but i cant afford anything better! :P)

My problem is, whenever I try to use guitar effects programs like GuitarFX and Guitar Rig, all i get is a massive squeal.

If i get out of the effects programs, I can hear my bass fine (microphone off mute).

Its only when i'm in the programs that the squealing occurs, i've tried turning down output and input in the programs, but to no avail.

Has anyone else had this problem / know how to fix it?