Run the cleanup tool first:
Cleanup tool - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=828910&SiteID=2
Then see this KB article for the 0020 error:
http://support.microsoft.com/kb/930162
Don't use the CD to install, but install the trial from http://onecare.live.com and then subscribe/activate by signing in with your subscription LiveID.
If that does not resolve the problem, please contact support.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
For your printer, the message from OneCare would simply mean that you would not be able to share this printer using OneCare's printer sharing feature. If the printer is not working and it is locally attached to your PC, contact Lexmark for help on getting it working.
-steve