I see this problem when I use following code in my workflow custom process.
@Reference
private ResourceResolverFactory resolverFactory;
I see a previous thread with the same subject in https://forums.adobe.com/thread/1204006?tstart=0
I tried the workaround mentioned in the thread, it didn't work for me(one of the workaround is by adding -XX:-UseSplitVerifier option to the JVM .This issue seems to be an with CQ 5.6 and java 7). I already have this in my start.bat and quickstart.bat
Here are Java and CQ5 versions I tried
Java 1.7
CQ: Version 5.6 and 6.0 (Didn't work on any one of them)