Screen freezing and going dark blue?

Question

I have had my Macbook since July 2014, I bought it from the Apple shop, and recently the screen has started freezing spontaneously and going dark blue. Nothing I press affects it, and it comes back after about half a minute or longer. Nothing specific seems to trigger it, sometimes it happens when I am not even touching the laptop.
Also, the Caps Lock doesn't always work, even though there doesn't appear to be anything wrong with the button, it only works selectively.
Is this a common problem, what should I do?

Answer 1

When you next have the problem, note the exact time: hour, minute, second.
If you have more than one user account, these instructions must be carried out as an administrator.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Console in the icon grid.
Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select
View ▹ Show Log List
from the menu bar.
Scroll back in the log to the time you noted above. Select any messages timestamped from then until the end of the episode, or until they start to repeat, whichever comes first. Copy the messages to the Clipboard (command-C). Paste into a reply to this message (command-V).
When posting a log extract, be selective. In most cases, a few dozen lines are more than enough.
Please do not indiscriminately dump thousands of lines from the log into this discussion.
Important: Some private information, such as your name, may appear in the log. Anonymize before posting.