intermittent 'silences' on recordings

hello all,
audacity on windows xp…perfect but on windows 7… I keep getting intermittent short spaces of silence so it becomes unusable, has anyone experienced this problem, what is the solution?

How intermittent and how short?

Win7 takes up a lot more of your machine than XP did. Does your machine qualify for Win7? Just barely won’t do it. You have to have enough machine left over to also do live audio.