Q: Installing memory

If you chose the memory from the Crucial memory selector, it should work fine. That error indicates it's the wrong memory or physically damaged memory. 

However, to reset everything, do an SMC reset: http://support.apple.com/kb/HT3964 . If that doesn't change things, also do a PRAM reset:

1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.

Next to the space bar, on either side.

Make sure you're inserting the memory sticks fully - they take a very firm push to seat, and you should feel a little soft click as it engages the contacts.