Based on your screenshot, it looks like you are using a very old version of MyEclipse. The issue could be caused by using a dated version of Java, a 32-bit VM on a 64-bit install of Windows.
If you can attach your error log here, we might be able to assist further, but I would suggest installing a more recent, 64-bit version of MyEclipse 2017. If you are a licensed customer, you should have access to all versions of MyEclipse while your subscription is active.
Thanks for letting us know that the problem is solved with the latest release of MyEclipse.
The activation code should work, provided your license is valid. However, given that you were likely using a very old release of MyEclipse, I suggest to re-enter your license details and activate again. To re-enter your license details, please refer to this article. If you already have a current subscription, you can start at step 4 in that article.