Is it possible that it is some stupid add ? When I click more info on the alert I get redirected to http://www.avast.com/pl-pl/lp-security-information-pp?utm_campaign=Virus_alert&utm_source=prg_ise_60_0&utm_medium=prg_systray&utm_content=pl-pl_virus-alert&p_vir=al&p_prc=file://C:\Program%20Files%20(x86)\Mozilla%20Firefox\firefox.exe&p_obj=http://83.23.58.33/&p_pro=2&p_vep=6&p_ves=0&p_lqa=0&p_lsu=24&p_lst=0&p_lex=111&p_lng=pl&p_lid=pl-pl&p_elm=7&p_vbd=1289