avast 6.0 version not working

for some reason avast stopped working , the fix it button does nothing, the start program wont start it, the shields are disabled and wont let me enable, i just got internet and it was working for two days and now its not doing anything when i try and click on these i even tried to reinstall it , still the same, does anyone know what to do?

Have (or did) you another Anti-Virus installed in this system, if so what was it and how did you get rid of it ?

What is your operating system ?
What other security software do you have installed, firewall, anti-spyware, etc. ?

It is right. It usually happens when there are conflicts between your softwares