Macbook Pro finder error -50 appearing randomly I've done a lot of research about this problem, but cannot find solution. My mac randomly gives an -50 error - nothing can be written and ReportCrash is using like 200% of CPU... Restart helps, but only for a short period of time. I thought it is HDD problem, so I bought brand new SSD, but problem persists. I reinstalled OS, nothing helped. I also downgraded from OS X El Capitan to Yosemite, but nothing helps. 

It totally drives me crazy, because I use my Mac for presentations for big audiences, and when it happens when I am presenting, it is horrible.

Thank you all for helping!
(Sorry for any mistakes, not a native speaker :) )

Macbook pro 2009 13" |
4 GB RAM |
2.26 GHz C2D |
240 GB Kingston SSD |
OS X Yosemite |
Since it's out of warranty your options are a bit limited. I would start by bringing to the Apple store for diagnostic, or read here for how to get your own hardware diags.  You have already reinstalled a fresh OS on a new drive, so it's possible the SATA cable is bad (believe it or not I've seen this happen), or even the logic board.  

What errors are reported in Console log when the problem occurs?