What would cause a tempo change mid song and how do I get rid of it? is it a setting that I may have accidentally triggered?

The scenario is that I have set the tempo to 120, used a real track style but about 8 bars into the song it changes to 128.999 (or something like that) for 6 or 7 bars and then changes back again. it wasn't like that when I first loaded the style, it just started happening some time later.

I couldn't find anything in the help files to assist.

Cheers

Andy


Andy

Macbook, 2.4 GHz, Lion OSX, 4mb RAM running Windows 7 through a Bootcamp partition,
750Gb 7,200 RPM hard drive, Ultra Pack fully installed on HD