I have a LaserJet 2200 series which completely opens up in case something gets stuck by the rollers, or whatever they're called.

Try opening up the printer and taking out the toner cartridge. See if you could find a staple anywhere under there??

Does the imprint repeat itself? If so, you might have a scratch on the drum or debris on one of the rollers. If you have a sheet with two such marks, roll up the paper until the marks meet, and that is the diameter of the roller ( or drum ) that is giving the problem. Usually the diameters of the varoius rollers are different, and this will tell you which roller needs cleaning. If it is the drum, that you need a new cartridge, which will give you a new drum.
As far as the crease: if the paper cants as it goes in, you might get a crease. make sure the paper feeds evenly into the printer, and that one side is not being pulled in 'faster' than the other side. There are products on the market called 'rubber rejuvinator' or some such name that will restore the friction to rollers so that they feed the paper properly.

Well, I found out the problem: There is wear and tear on the rubber belt that is in it. Faulty product. Thanx for the help guys