I make sure that no other programs that will use up my sound card are open at that time. (Like YouTube, iTunes, or any other type of recording software)
What soundcard are you using? Is it an on-board one? Windows itself can cause problems by trying to play out it's own bings and bongs which can take over the soundcard and alter settings. So you need to go into the Windows' Sound Settings panel and make sure that "Windows Sounds" are set to "None".
Yes, we need more details of the sound card(s) being use and things like drivers etc. However, a couple of comments:
First, turning off system sounds is absolutely necessary in Windows for any serious sound work. The bings and boops that Windows generates will all upset your sound work. Also, for a problem of a skipping playback, go to Edit/Preferences/Audio Hardware and (assuming you're using MME drivers) increase the latency setting. This will increase the buffer size and make your playback more stable.
Second, for Jammin101, when you say files won't play back, are you getting skipping like the original poster or no playback at all? If the latter, does the system just sit there and refuse to do anything or does the cursor move on the waveform display but not give you any sound?