LATENCY ISSUE

this is the second time i have ever posted anything on any type of forum ever, and, from what i have seen people get really mad when you post the wrong thing in the wrong place. that said, its my first time, go easy on me. thanks.

i have the fast track pro USB interface. I am using Ableton live 7.. the 14 day trial version. i have had it for only 2 days.

yesterday was great...

today... horrible latency that makes me feel like i am on some kind of
downer when monitoring...

the latency tab under preferences ... i went there, i used the test tone... moved the buffer size up and down... the tone never sounded clear, it was consistently buzzing and squealing... not popping and clicking but worse... like i said, yesterday, it sounded great around 93 samples..

all i am trying to do is record a few vocals tracks over an MP3 i imported..
i was gonna throw a couple effects on later.. this is a very simple project and doesn't require tons of tracks and effects...

what else? i am using a macbook... check it..
Hardware Overview:

Model Name: MacBook
Model Identifier: MacBook2,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache (per processor): 4 MB
Memory: 1.5 GB
Bus Speed: 667 MHz
Boot ROM Version: MB21.00A5.B07
SMC Version: 1.13f3
Serial Number: 4H70517VWGM
Sudden Motion Sensor:
State: Enabled

the sound card is the stock card ..check it..

Intel High Definition Audio:

Device ID: 0x83847680
Audio ID: 34
Available Devices:
Headphone:
Connection: Combo
Microphone:
Connection: Internal
Speaker:
Connection: Internal
Line In:
Connection: Combo
S/P-DIF Out:
Connection: Combo
S/P-DIF In:
Connection: Combo

ok! sorry for providing too much or too little info...
people who actually help people on the web are tight i mean awesome and i aspire to be just as generous when i build myself a nice body of knowledge as well..

anybody?

thank you!