I have been dealing with Mac's for over 20 years. Bought my first in 1984. The point being..... even if I gave you the description of the 2066 error, it would mean very little to you. It doesn't help.
It's more important to know which model you have, what OS (Operating System) you are running and what you were doing or what program you are running when the fault occurs!
Problems like your having do crop up, especially on Laptops because the internal hard drive gets bumped and corrupts data.
Depending on what data gets corrupted as to what the Error is.
Bottom line is, the machine needs some service about every 1-2 years to eliminate problems creeping in.
But.... You have a Mac.... So It's pretty straight forward really!
I have been using the following method for years.... SO.....
The best advice I could give you is....
Purchase an external 3.5" Hard Drive.(more robust than 2.5" pocket drives) About 1 TerraByte should do.
If you have a FireWire Port on your Mac then get a Hard Drive with a FireWire connector on the back... its faster,
Otherwise use the USB Port. (USB 3 Better)
Use the DiskUtility Program to Format the External Drive to Mac OS Extended (Journaled)...... Name the Drive something like "External Drive"........Now its ready for use.
Go on-line and download CCC (Carbon Copy Cloner)
Use this to make a Clone of your current Internal Hard Drive (Source in ccc) to the external Hard drive (Destination in ccc) This will take some time depending on size & content of your internal drive. Fifteen minutes to an hour.
Once completed, you should prove that the Clone is good by BOOTING from it. Restart & hold OPTION KEY DOWN & choose your new external drive. Once booted from external "Clone" you know for sure that the clone is a fully functional copy of your internal hard drive. Change the Desktop Picture in System Preferences so that it's different to your existing system. This is to avoid getting mixed up between Booted Systems (clones look the same)
The System Preferences / Startup Disk is also a useful tool here.
Now that you have a fully functional working bootable copy ("Clone") of your hard drive, you are SAFE from loosing any of your personal data. I make a new clone every few months to be Safe.
Now..... To rid yourself of all bugs & errors & faults and defragment your hard drive & update to a better (newer) version of the OS
ALL IN ONE HIT. and end up with a clean computer just like you originally bought. All you have to do is wipe your internal hard drive of everything. That is...ReFormat it with Disk Utility
(external drive unplugged for safety).
Then re INSTALL (takes about 20 minutes) a new clean (updated version) of the OSX. This is now free from Apple Downloads. e.g. OSX 9.1.2 (Maverics)
Then you can do one of 2 things.
Re enter all your details & passwords & Apple ID & Network details when prompted after re booting the new installed OSX OR
Choose Migration Assistant to put all of your stuff back in place like it was before you started. This usually works fine BUT it can put back faulty Apps etc that were causing problems before, so be choosy in what you put back (it allows you to select items)
Obviously it would be wise to have already downloaded the newest OSX for your Mac first. And even do a practice install on the external drive to see how the install process works.
You could partition your new External Hard Drive into 2 Partitions of say 500GB each. One for your "CLONE" and one to experiment with the Install OSX Process.
You could even set up the New External Hard Drive with the New OSX e.g. OSX 9.1.2 (Maverics) first then "Migrate" all your old software back on to this drive. Boot the drive & test it for faults etc. Try for a couple of days. Then Re Clone it with CCC back to your Internal Hard Drive for permanent daily use.
It's up to you.... But having an external CLONE gives you so many advantages. You are using Apple Technology and ease of use here! So it's easy to do all this. Think yourself lucky, PC People would very rarely consider doing this with Windoz because it's just too difficult!