SiteBuilder keeps changing my page width

I have my page width set to 1000 for each of my website pages.  However, my setting in Sitebuilder will change for just one page or another and for random settings - it could be 1100, 1250, 1600... whatever it's in the mood for that day, I guess.  It's been doing this for months without explanation.  I will reset it and it will stay for awhile and then just randomly change.  It's never the same page, it's completely random.