Scratching noises on delayed playback

[MoonlightPathetique]

I just installed Finale 2010 on my new laptop. Whenever I run the playback on a composition for a large number of instruments, it takes a very long time after I hit play for it to actually play, and when it does, the sound scratches and buzzes very much. Also, the sound gets progressively farther behind the green bar as the piece goes on (and sometimes measures are repeated). I have no such problems on my desktop computer, though both have the same amount of RAM. Any solutions or explanations would be greatly appreciated.