I did not read all of the posts so if I am duplicating an answer, please forgive me. When I couldn't put my hands on my "single" hole plate, I taped a credit card over my plate with a hole punched in it. Now you probably cannot do that when sewing because you cover up your feed dogs. It did work for me while FMQ. Also, a new needle is good advice.

I was gonna put my two cents in; but ya all beat me to it !LOL :-)

My 6500 tends to want to do the same.
I hold the top and bobbin thread until the feed dogs have a good grip. OR I'll use a small piece of fabric and let it go through first..I think they are called "leaders"
I love my Janome but not as good as I love my vintage machines. No problems with them eating fabric..

Milli, you got great advice. I have had similar experiences with every machine, from the 1960's Pfaff I learned on, to my Janome today. What everyone says about starting your seams works like a charm. Sometimes just holding your starting threads is all you need to do.
As for the troubles you have sewing over bulky layered seams, using a nice sharp needle in the correct size helps a lot.
If that doesn't do the trick, try using a "hump jumper". It's a little gadget that helps you sew over layers without ending up caught there. Sometimes these are called a "button reed" too, because the tool is used when you sew on a button by machine, to make sure there is a bit of a thread shank under the button.
You just place the hump jumper under the back of your pressor foot so that the foot is no longer climbing up at an angle. This effect can be duplicated by using folded cardboard too. The hump jumper also helps when coming off the layers where you often end up with a skipped stitch. (You reposition it to the front of your pressor foot)

Pulling the thread tight from the back when you start out keeps the fabric from getting crunched up, also by leader fabric they mean, start on a small scrap of fabric and place your project fabric next to it and sew right onto your fabric from there. My Bernina has the same tick, my 40 year old Elna SU didn't have that problem.

I agree with cindynvb. This is what I do to avoid bird's nest and eaten material.

I have never heard of a straight stitch plate. Can someone please explain more about it? I have a Janome 6600 and am very interested.

Try a smaller needle?

A straight stitch needle plate has a single hole for the needle so you couldn't zig zag. There is no room for the fabric to be pulled into. Great for piecing and FMQ.

http://www.amazon.com/Janome-Straigh.../dp/B002EZS0CO

I haven't seen this yet. But when I had issues I found out in accident that if I keep the needle down and put the fabric against the needle then it doesn't get eaten. Now I am in the habit of holding the thread tails as well and using leaders. I figure I need all the help I can get lol