What kind of percentage/poundage were you increasing each week? I'm on week 6 right now, and things feel great. i've been moving up 10# a week on the squats, and 5# on the pressing stuff, 15# on the DLs (though I had to start lower than expected)
Maybe you've increased weight quickly enough that here at week 6, you simply haven't adapted to the level of being strong enough for these weights. My contingency plan in a situation like this would be to ..
1) Eat more
2) Drop weight to week 3 or 4 levels. Maybe you'll be able to increase by the end of the program to be up to where you'd be if you had progressed linearly to week 7. I'm sure that the volume and intensity will still be enough to cause some growth. Hey, that's what we're particularly worried about anyways in this situation.