If you are not getting a virus warning that and you believe it is a new, undetected virus, then if you can zip and password protect (‘virus’, will do) the suspect file and send it to virus @ avast.com (no spaces).
Give a brief outline of the problem (possibly a link to this thread), the fact that you believe it to be an, undetected virus and include the password in the body of the email. Some info on the avast version and VPS number (see about avast {right click avast icon}) will also help.
AntiVir Found Trojan/StartPage.afb
ArcaVir Found Trojan.Startpage.Afb
Avast Found nothing
AVG Antivirus Found Startpage.SZ
BitDefender Found Trojan.StartPage.CY
ClamAV Found nothing
Dr.Web Found Trojan.StartPage.1092
F-Prot Antivirus Found nothing
Fortinet Found W32/StartPage.AFB-tr
Kaspersky Anti-Virus Found Trojan.Win32.StartPage.afb
NOD32 Found Win32/StartPage.ABP
Norman Virus Control Found W32/Startpage.BWB
UNA Found Trojan.Win32.StartPage
VBA32 Found Trojan.Win32.StartPage.afb