I woke up a couple of hours ago and I know that my site got 500-1000 visits while I was sleeping, but analytics only shows 65. I didn't change anything on my site, so this must be an external error. Has anyone else noticed this, or am I the only one?
I'm having the same issue - comparing stats from my web host, Google is only showing stats for about 10% of my traffic. Very odd...
Analytics only measures real users (doesn't measure bots or anything else that doesn't support JavaScript). Pull your weblogs and verify what you were seeing weren't just bots or spiders.