Does anyone know if my E-Ticket is missplelled by one letter, if this will cause a problem?

Your name is mispelled? Theoretically it should match whatever ID you're also presenting. I'd call the airline to get the straight scoop on this one. I've seen them drop letters off the end of a long last name. Better to be safe than sorry though. Call the airline and ask them. It may be a simple matter to reissue the e-ticket or make a note that comes up when you check in that the ticket counter knows of the mispelling.