eclipse freezes in ubntu 16.04

I'm running ubuntu 16.04 on a dell xps 13, and I had java eclipse running ok. I did a mercurial commit from the command line, and I had some conflicts related to the eclipse metadata files.

I managed to get the commit taken care of, but I'm honestly not sure what I did to the project metadata files.

I was not able to get my web project started, so I re-set all the build paths, runtime environments, new server and so on.

Then, the server just wouldn't start...no error, just totally non-responsive.

Then I tried to create a little helloworld class, just to see if I could get something to run, and creating the new class took forever...it hung with the revolving wheel.

I googled around, and looked in workspace-dir/.metadata/.log and saw this:

eclipse.buildId=4.5.1.M20150904-0015
java.version=1.8.0_91
java.vendor=Oracle Corporation
BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os linux -ws gtk -arch x86_64 -product     org.eclipse.epp.package.jee.product

!ENTRY org.eclipse.ui 4 0 2016-05-12 17:43:04.325
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException

and from today there is this:

!SESSION 2016-05-13 16:50:12.337 -----------------------------------------------
eclipse.buildId=4.5.1.M20150904-0015
java.version=1.8.0_91
java.vendor=Oracle Corporation
BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os linux -ws gtk -arch x86_64 -product     org.eclipse.epp.package.jee.product

!ENTRY org.eclipse.core.resources 2 10035 2016-05-13 16:50:18.341
!MESSAGE The workspace exited with unsaved changes in the previous     session; refreshing workspace to recover changes.

!ENTRY org.eclipse.jst.jsp.core 4 4 2016-05-13 16:50:28.629
!MESSAGE A workspace crash was detected. The previous session did not     exit normally. Not using saved taglib indexes.

wasn't sure what to do...maybe just delete eclipse and re-install?

Update

I deleted the eclipse folder, and reinstalled. Now having the same problem when trying to cfeate a simple project from scrath.

I also deleted the ~/.eclipse folder, all workspace folders and tried again, having the same behavior

this is my java version:

openjdk version "1.8.0_91"
OpenJDK Runtime Environment (build 1.8.0_91-8u91-b14-0ubuntu4~16.04.1-b14) 
OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)

was able to compile/run simple class using vim in terminal

eclipse download I'm using is:

eclipse-jee-mars-2-linux-gtk-x86_64.tar.gz

thanks!