Here is what happened to me: I am trying to install magento on my local xampp, and I run into a screen that tells me that I must load curl and mcrypt. No biggie. I look for the php folder, locate the php.ini and uncomment the two lines. I restart apache. I start the installation process again, and guess what? Nothing. I ran into the same problem. I restart again. The same issue.

Time to google this one. I tried several tries until I hit this page:

http://www.zen-cart.com/forum/showthread.php?t=75924

In the thread I learned that the php.ini that xampp uses is not located in c:\xampp\php, but in C:\xampp\apache\bin

Of course it works right after that. :)