Finder Crashes All The Time - Mountain Lion.

Question

Helo there,
My iMac used to work just fine, but now after a year I got it, Finder crashes all the time. It doesn't show my folders, only some of them. I have to search to see them. When I open Finder, and try to work with it, I will get the loading colloured cirkel. Also Finder's sidebar doesn't show my favorites, airdrop or all my files. I can only see shared computers and extended drives and usb's. I've got two extended harddrives connected to my Mac, both of 1TB. One of them is my TimeMachine and the other is my old drive with movies. When I open the TimeMachine drive, I works just fine but when I open my older drive it will load very long and then show nothing. If I want to upload a picture on facebook or something like that, and I get the window to choose the file, it will lagg, stuck and not work, cause I can't see anything. I have to search it then with spotlight, and then select it. When Finder chrases and stuck with the spinning wheel, I restart Finder with second mouse option. Then I will have to wait very long until it opens again. The stuff on the desktop dissapears and I can't draw a selection area anymore. Also other programs crashing a lot more often, like disk utility and activity monitor. I thought it was immposible to work with a computer that crashes all the time. So what I did was:
Checking my harddisk with disk utility, and recover the things
Still stuck with the problem
Then
Make a TimeMachine backup.
Reboot the iMac holding the option key
Erase harddisk
Reinstall Moutain Lion
Reinstall backup
Repairing disk with disk utilities again
After this, I got the same issue and it drives me crazy. I've been to two local Apple resellers and told them my problem. They told me that it probably was a hardware issue. I have no idea my self so I ask you guys if you can help me out with this.
By the way:
one time when I restarted Finder, it wouldn't open and I got error code 600.
Last software that I installed was Paragon, I thought that it was causing the problem, so I deleted but it dind't helped. Now I got Paragon again.
Is this a software or a hardware problem and how should I fix this?
Thanks.

Answer 1

Please read this whole message before doing anything.
This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.
Step 1
The purpose of this step is to determine whether the problem is localized to your user account.
Enable guest logins* and log in as Guest. For instructions, launch the System Preferences application, select Help from the menu bar, and enter “Set up guest users” (without the quotes) in the search box. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your personal files or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.
Step 2
The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards. Boot in safe mode* and log in to the account with the problem. The instructions provided by Apple are as follows:
Shut down your computer, wait 30 seconds, and then hold down the shift key while pressing the power button.
When you see the gray Apple logo, release the shift key.
If you are prompted to log in, type your password, and then hold down the shift key again as you click Log in.
Safe mode is much slower to boot and run than normal, and some things won’t work at all, including wireless networking on certain Macs.  The next normal boot may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
*Note: If FileVault is enabled, or if a firmware password is set, or if the boot volume is a software RAID, you can’t boot in safe mode.
Test while in safe mode. Same problem?
After testing, reboot as usual (i.e., not in safe mode) and verify that you still have the problem. Post the results of steps 1 and 2.