Can I sue my former employer?

I live in the sate of California. I worked at a cardiology office for almost 10 yrs and was fired 01/05/10 as involuntary termination due to work performance. To receive unemployment insurance I had to go through a telephone interview. I told them exactly why I was fired. Never any warnings and was always a reliable, honest and dedicated employee and they fire me for work performance. When EDD called my employer my supervisor told them I was fired for altering patient accounts. I was so upset over what I read and could not sleep for days wondering what I could do about this. I decided to just let it go but it has been bugging me now for several months. Is there anything I can do as file a claim against my former employer for lying about why I was fired? and if so what is the statue of limitations and what can I sue them for (slander, defamation of character). I know I probably should have done something after the phone interview but I was so upset. Anyone out there have any suggestions?