Joomla: 500 - An error has occurred

I got a strange error when I tried to login to the Administration section of my Joomla(1.7) installation. After I entered my login name and password and hit the singin button, I got the following error!

"500 - An error has occurred - Return to Control Panel"

500 - An error has occurred - Joomla

However, I could access the site(front end) without any problem. That didn't help me because I can't do any configuration changes without entering the administrator section(back end).

A Google search for the error message returned thousands of results. It looked like many people had this problem. 

The Solution:

Though it took couple of hours of going through results and tweaking the folder/permission settings on my hosting server, I could solve this problem.

This is what I did to solve the mysterious "500 - An error has occurred" problem:

I logged into my hosting server. Then in my Joomla installation directory, I changed the permission of following folders to 775.

• administrator/cache
• cache
• logs
• tmp

And it started working! I could login to the Joomla Admin Page of my site! I managed to solve the problem without understanding the problem!

If you have run into same/similar problem, and/or you know a better solution feel free to share your story in comments.