I want to preface this by saying that I am very new at wood cutting and the MS290 is the first chainsaw I have ever owned - just purchased last weekend. I have been doing a lot of cutting with it this week and for the most part the saw works well. However, when I get into a 'big' piece of wood there are times when the chain will stop turning. I don't think it's a case of the bar/chain getting pinched because the log is already flat and down on the ground. The bar/chain oil is topped off so it's not an oil issue. Right before it happens I can really tell that the machine is struggling I can here it. If I sense that the chain is about to stop turning I pull up a little and it kicks in again full speed then I am able to cut for another 5-10 seconds before the chain stops again. Smaller logs are no problem it's just the big ones that are giving me trouble. The type of wood being cut is black walnut and birch - it is happening with both types of wood. I thought that perhaps the chain isn't sharp enough but the dust is still in pretty big flakes which I understand is an indication that the chain is 'sharp enough'...any suggestions would be greatly appreciated. Thanks folks. Tom