What Operating System are you using ? is it up to date ?
What actions have you taken to try and resolve the problem ?
What is the infected file name, where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ? Check the avast! Log Viewer (right click the avast icon), Warning section, this contains information on all avast detections.
Do you mean it can't be removed or dealt with or it keeps coming back, can you expand ?
I haven't checked the log file, but it would have been better if you had left it in the post. That way it is available to be viewed as a reference by those checking the topic without having to download a file (firefox).