How to set a timeout on WMI queries?

I have a .NET application which runs WMI queries on all domain computers in order to find the logged in user; it pings each computer to find whether it is online or not, then runs the actual query.

Code snippet:

try
{
    string loggedonuser = null;

    string computername = "ComputerToQuery";

    ConnectionOptions co = new ConnectionOptions();

    co.Username = "DOMAIN\MyUser";
    co.Password = "MyPassword";

    co.Impersonation = ImpersonationLevel.Impersonate;
    co.Authentication = AuthenticationLevel.Default;

    ManagementPath mp = new ManagementPath(@"\\" + computername + @"\root\cimv2");

    ManagementScope ms = new ManagementScope(mp,co);

    ms.Connect();

    ObjectQuery oq = new ObjectQuery("SELECT username FROM Win32_ComputerSystem");

    ManagementObjectSearcher mos = new ManagementObjectSearcher(ms,oq);

    foreach(ManagementObject mo in mos.Get())
        loggedonuser = (String) mo["username"];
}
catch(Exception e)
{
    // Handle WMI exception
}

The problem: sometimes the WMI query hangs on indefinitely.

How can I set a timeout on it?