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Hey there caboodle. As far as I can tell, the LaserJet 2550L is not supported with Lion (10.7). I do know there was a similar issue in 10.6 that had a "work-around." You can try this and see how it works for you in 10.7:
Using Mac's Finder, go into System folder, then Library folder, then Extensions and then move hp_Laserjet_io_enabler.kext into Trash. Reboot mac.
Be sure to reboot the computer afterwards. You may also have to delete the old printer queue and setup a new one after also.
Let me know if this works and Good luck! 
Sorry. Did you recently upgrade to 10.7?
Hum. Let's uninstall with the 'scrubber option' like this:
1. Go to Applications/Hewlett Packard/ click on HP Uninstaller and click Continue
2. Highlight your device on the left pane
3. Hold the Ctrl, Opt and Cmd keys and click on Uninstall
4. There will be a pop up that asks if you are sure you want to uninstall ALL hp software. (At this point, if you continue, any HP printers you have installed will need to be reinstalled)
5. Click Continue and let it finish
Now, run a Software Update. This can be done by clicking the Apple in the top left of the screen then clicking Software Updates.
Next, let's reset the printing system:
Go to System Preferences > Print & Scan
- Right (or control) click in the rectangle listing your printers and select Reset Printing System.
WARNING - this will delete ALL of your printers!
- Select the plus sign to re-add a printer. Select the Default tab on the top of the window. Look for the printer, select it and wait until the "Add" button becomes available. Click it.
Let me know how this works for you.
