Which 7000 error code are your receiving?
From what I have gathered, the ER 7061 code is for the hard drive and the ER 7071 code is for the dvd drive.
If it's 7061, swapping the hdd may solve this problem. Make sure that you use the recommended replacement drive.
If it's 7071, shut the unit off by holding the power button until the time is displayed (instead of the error code). Unplug the unit. When you open the case, you will see a white plastic piece at the front of the dvd drive near the silver plastic hinge on the face of the unit's dvd opening. The white plastic piece slips in the groove of the hinge to stop the units dvd door from being opened while the drive is engaged. Push the white plastic piece in toward the dvd drive; sometimes the mechanism gets sticky. Plug the unit back in and press the power button. This may solve the 7071 error.
Hope this helps.