I tried printing text including elaborate colorful artwork on the pages. Some of it printed but the text became increasingly smeared. Finally it would not print any more. Hours later I tried copying a normal page of type but while the lights came on the printer would not operate. What's wrong, and how to fix it? Any help appreciated. (HP Deskjet 6540)

Try updating print driver

Included general maintenance video and how to clear smears from the paper.

Solution: Remove Print Smears / Printing Fuser Cleaning Pages
7750 Support Knowledge Base Remove Print Smears Fuser Cleaning...

With Troublshooting highlighted on the printer display perform the following steps:

1. Press OK.
2. Press the Down Arrow and scroll to Print Quality Problems.
3. Press OK.
4. Press the Down Arrow and scroll to Remove Print Smears.
5. Press OK. The printer will print 5 cleaning pages.

Repeat this process five or six times, to remove stubborn toner buildup from the fuser.
Always make sure you are matching the type of paper loaded in the printer tray(s) to the correct Paper Type front panel setting. When you load a tray with paper, the front panel will ask you to indicate the type of paper you loaded. For correct print quality and printer operation, be sure to set this correctly.
MAINTENANCE:
Phaser 7750 Video Instruction Maintenance for the Printer Phaser

Welcome to FixYa!
Solution 1. You might want to check the ink levels of your printer. One of the ink color might be out. Your printer uses the C,M,Y (one cartridge) and K (another cartridge). The printer mixes this colors (C,M,Y,K = cyan, magenta, yellow and pink) to produce the right colors including black.
Solution 2. Please do a printer head cleaning. You can do it using your printers software maintenance option.
Thank you for using FixYa.Have a great day.

You didn't include make and model of your printer so we can only guess. My guess is that you don't use the printer daily or for many documents and the printhead is clogged with dried ink.
I finally got tired of cleaning printheads so often and went with a color laser printer; it costs more to run but it at least prints when told.

If the ink is smearing, it probably is not getting enough drying time. The ink drying time is a period of time inserted between pages to reduce the chance that a page will smear the one below it in the output tray. This time is factored into the time between when the first page finishes and when the next page finishes. Printing will pause temporarily if more time is needed. The time it takes for ink to dry varies greatly depending on paper type, printer driver settings, humidity, and temperature. In addition, the paper and print settings may affect the speed at which the ink can dry:

• Transparencies require much longer drying times than other paper types.
• Some store-branded photo papers do not allow ink to dry correctly because of the coatings used in their manufacture.
• Printing in Best mode can increase the dry time.

Resolving the problem If the ink smears, increase the drying time. To increase the drying time in Windows, follow the steps below:

1. When ready to print, click File , click Print .
2. Depending on your driver version, click Properties , Settings , or Preferences and follow the steps below depending on the option.
   • For Properties or Settings , follow the steps below:
     1. Click the Advanced tab.
     2. In the Extra Dry Time section, move the slider toward More .
   • For Preferences , follow the steps below:
     1. Click the Basics tab.
     2. From the Basics tab, click Advanced Features .
     3. In the Extra Dry Time section, move the slider toward More .
3. Try a sample print and see if the drying time needs to be increased more.

To increase the drying time for a Macintosh computer, follow the steps below:

1. From the File/Print Menu , select Ink under the General tab.
2. In the Dry Time section, move the slider toward More .
3. Try a sample print and see if the drying time needs to be increased more.

Other steps that will reduce ink smearing If the ink still smears when printing, try some of the following suggestions:

• Decrease the amount of time it takes for the ink to dry by decreasing the print quality to Normal or Fast mode.
• Try printing on a different type of paper or on paper from another manufacturer. Paper formulas are different between manufacturers and may have a coating that causes the ink to be absorbed at different rates.
• When printing large graphics or photos on plain paper in Best or Normal modes, improve the results by using heavier paper. Paper that is rated at 90 g/m2 (24 lb.) or higher will not curl or smear as easily as paper of a lighter weight.

Increase the bottom margin, the HP printer driver will automatically crop whatever is outside the printing area. Including text and images.

Try placing sheet of black text on copy board, and run many copies black only. I ran 25x12 times still no black. Run head clean after about each 50 sheets. Persevered and finally BLACK ink OK Inkypete

There are 2 reasons for this either the ink is drying out nor your page settings isnt set to the correct size of the paper you are printing to.

Looks like the ridges inside the cartridge are catching. Here's a solution;

http://www.ahfx.net/weblog.php?article=133

Try to change the default printer and check ...

Also try printing from other documents see if you facing the same problem

What version of Works you using ?
Do you have the Dic for Works ?