Anybody knows what's going on here? (boot up issue)

Macs are not immune to malware, but no true viruses exist in the wild that can run on Mac OS X, and there never have been any since it was released over 12 years ago. The only malware in the wild that can affect Mac OS X is a handful of trojans, none of which produce the symptoms you described.

Read the What security steps should I take? section of the Mac Virus/Malware FAQ for tips on practicing safe computing.

 

Could be a bad internal video connection - open up and check that the LVDS cable is properly connected.
Or, it's a bad LCD panel (the display itself), or failed logic board.
Hook up an external display to see if the display appears OK on the external. If it's good, then the internal display is faulty.
If you get the same bad image on the external, then you can assume that the logic board has failed.

 

What model is your Macbook?
What year was it made?

 

Run Apple Hardware Test, or Apple Diagnostics:

http://support.apple.com/en-us/HT201257
Important: If your Mac was released after June 2013, you will use Apple Diagnostics rather than Apple Hardware Test (AHT). See Using Apple Diagnostics for instructions.
​

 

if used customers hd for boot up maybe it looking for it. try holding alt down on start up to select your disc to boot from might work as did for me.