I resigned without notice from a job of 10 months recently due to questionable billing practices through Medicare for services not rendered. They were suddenly under investigation by the OIG/FBI and I was concerned for my professional license. I even put in a deposition as a witness to the prosecution. Believe me, when you go down to FBI headquarters and spend 4 hours talking to agents and attorneys it's extremely stressful.
When a new employer sent them a survey on my work performance they checked off negative responses and stated I was not eligible for rehire. I had three formal performance reviews in my time there that were all excellent. My new employer heard my side of the story at the initial interview but refused to call my immediate supervisor from that place for a work reference that would have been highly positive. She let me go a few weeks later before my probation was up by saying I used her computers for personal use (internet use during slow times). I didn't even have an opportunity to discuss the situation and simply left.
What now? I did not give them permission to contact that employer for obvious reasons (they weren't too thrilled to have me leave all of a sudden). I don't want future businesses getting the same information back.