I have a problem with Jack ! i need jack for guitar effects

[xrhstaras]

I have a problem with Jack ! i need jack for guitar effects with apps : guitarix,rakarrack
I must say there is a big problem with jack on this version ! Cannot be used i dont know why .
It didn't worked at all then i tried some configurations and now its wokring very very very badly !
Its even have feedback noise like a SIREN when i increase the volume of mic input.
Its very strange cause i dont have any other microphones connected and i use it with an electric guitar that has magnets so it can't have feedback its Jack's problem and it SUCKS completely !
I hear strange noises and has bad quality , its filled with noise !
I never had similar problems so i believe something has to do with the JACK
When i dont use jack i can record normally without any problems!!!

Why on linux always must be something that doesn't work ?
I used the last two years jack without any problems...on the same machine and now its like crazy i dont know......

It seems like i can't do anything for this problem...so desperate