Spend a little time searching the topic on google and even this post. It appears that this has been a well documented problem since at least early 2008. The problem appears to be the imaging unit. According to several posts, Samsung has replaced several of the units. I purchased my CLP-300 in November 2008 and it worked with no problems until about 8 months in. The black text would print very lightly on the left side of the page about 1/4 of the way into the page. There was also a streak that ran down the page vertically that disrupted the text. I could change the font to any color and it would print just fine. After replacing several toner cartridges, I just began to print in a dark color for many months. After discovering all the posts on the internet this week, I contacted Samsung today with my documentation and evidence. They basically blew me off stating that I was outside of the 1 year warranty period and there was nothing they could do. I was even hung up on by a Samsung employee named Michael. Tonight I plan to take a hammer to it to relieve a little frustration. I cannot understand why Samsung chooses to ignore this well documented problem. Good luck.

I had this problem with a non samsung toner cartridge when i replaced it with a different brand non samsung one it cleared up after printing enough pages to clear out the other toner