Hi Marmon,
Reinstalling your PIXMA MX870 may resolve this issue. Please follow these steps:
1. Right click the Windows Start Menu button in the lower left hand corner and left click Control Panel.
2. Under Programs, click on Uninstall a Program.
3. Click on the Canon MX870 MP Driver and then click Uninstall at the top.
4. Follow the prompts to uninstall the driver.
5. Click on the Canon IJ Network Tool and the click Uninstall at the top.
6. Follow the prompts to uninstall the network tool.
7. Click on the Canon IJ Network Scan Utility and then click Uninstall at the top.
8. Follow the prompts to uninstall the scan utility.
9. Restart the computer once complete.
Please follow these steps to download the necessary files to begin installation once the computer restarts:
1. Visit Canon's website at: http://usa.canon.com/support
2. Type PIXMA MX870 in the "Enter a Model Name" box and click the Get Drivers & Downloads button.
3. Under Recommended Downloads, please click the Select button next to the MX870 series MP Driver.
4. If you agree, please select the checkbox next to "I have read and agree to the terms of the Disclaimer and wish to continue with the download".
5. Click the Download button.
6. If a Save As box comes up, click Save.
7. Press the <SETUP> button on your PIXMA MX870.
8. Use the left or right button to select Wireless LAN and press <OK>.
9. Use the up or down button to select Yes and press <OK>.
10. Select Easy setup and press <OK>.
11. Select your access point name and press <OK>.
12. Enter your wireless password and press <OK>. Please verify this password, as it is case sensitive and if entered incorrectly, will cause the printer and router to not communicate. To switch between letters and numbers, press the * key.
13. Press <OK> on the confirmation screen. The PIXMA MX870 will search for the access point.
14. When found, press <OK> on the Connected to the access point screen.
15. Back on the computer, open the Downloads folder.
16. Double click [mp68-win-mx870-1_06-ea24.exe] to begin installation.
For additional assistance, please view the PDF following this link:
http://downloads.canon.com/wireless/setup_350_870_win.pdf
If you continue to have difficulties, please contact our support group using the following link:
http://www.usa.canon.com/cusa/consumer/standard_display/contact_us_consumer
