Cheap but effective.
Start by doing the following.
- Delete the FILE autorun.inf
- Create a Directory called "AUTORUN.INF" on all partitions.
There is likely to be a registry entry in RUN or RUNONCE calling a DLL that is going to recreate the FILE everytime the machine is restarted.
By having the "AUTORUN.INF" FOLDER there, the system will not be able to create the file, thus preventing the system from recreating it.
When you reboot, you will receive an error saying something.DLL error.
That is one of the files you will need to delete.
After that, you will be able to re-activate your AV and clean the system.
Cheap but Effective!