Thanks Rui. The tray was already set to normal paper. So that leaves me with testing the Xerox paper. I'll report back as I'm finished testing.
Check tray settings. Make sure is set to plain paper, normal paper. If the tray is set to heavyweight the printer uses more heat on fuser. This way paper loses more moisture and you can experience the curled problem that you are having.
If the tray settings are OK, them you may have a problem with your paper. You need to take care your paper. If paper absorbs to many moisture you will have problems. Make sure to maintain paper closed and only open the package when need it.
To try to figure out what is happening try to open a new paper packet and load that paper on the printer and see the result. It the prints are OK it means you are not treating the paper right or your room may have moisture problems.
If the result is the same and the tray setting are OK, then the paper you are using is not the right one and you should consider test other brands.
Try Xerox paper because is cut as suppose to be. The cut is very important, it should be cut in a specific direction. If not, you will experience the same result.
When I print a b/w text page from - let's say - MS Word, single sided, it comes out quite curled.
I use 80 grams uncoated laser. With b/w printers I've never seen this behaviour.
How can I fix this?