Skipping noises when Audio editing...

every time i edit music in my laptop i keep getting these clipping/skipping sounds in the backround of my music and its driving me CRAZY!!! when i edit on my desktop i have no problems but my laptop cant seem to handle a few minutes of editing. Im using audio editing programs such as "Reason" "Cubase" etc. but they are all haveing the same issues. I took my laptop to "Geek Squad" and they told me it was a ram issue so i spent $200 on a new 1gb ram chip only to have the problem come up again. I dont know what to do and im running out of options..PlEASE HELP!!!

heres a link to an example of what im talking about. what ur hearing is not an audio mixdown of a session. I just played my project with "Reason" in real-time while i recorded the two sessions with "Soundforge"...

http://www.filelodge.com/files/hdd8/196794/GOOD - Reason Rock track.wav

http://www.filelodge.com/files/hdd8/196794/BAD - Reason Rock track.wav