The computer freezes every 10 minutes
After upgrading by my self memory ram up to 4 gb, all seems to go fine but now every 10 minutes I see some vertical stripes on both the sides of the screen, the mini freezes and I have to turn off the machine.
What I did wrong?
That should be the correct memory. Can you reinstall the original memory and see if the computer behaves normally. If it does you may have fallen victim to that rarest of problems--faulty new memory. If the computer runs correctly with the old memory return the new for money back or replacement. Check the numbers on the memory sent back so you don't receive it again. Good luck.
Are you sure you replaced the RAM with the right specs? If you are sure you did make sure you have seated the RAM properly. You can tell when the RAM is properly seated if you feel a slight "thump" when it's inserted completely. Your mini uses PC3 8500 RAM.