Proxy server asking for login ID and password

I am using Avast! 4.7 and have set proxy as localhost port 12080 for http connections.

For past sometime when I boot my computer, it will pop up a window and ask for login ID and password for proxy server. I just cancel it and everything is fine. This happens randomly i.e. not every time I boot I get this message.

Any suggestions why I am getting this error.

Are you using XP/Vista or Windows 9x?
Why did you set that proxy and where (Webshield or for updates)?

Windows Vista Home Premium.

Yes it is Webshield. I have set it in IE7 as well as in Mozilla Firefox.

For Windows XP/Vista, the scanning is transparent, you shouldn’t change anything.
These changes (and tutorials) are only for users with Windows 98 and Me.
For IE - broadband users: - Tutorial - Web Shield Proxy Set-up for IE
For IE - dialup users - Tutorial - Web Shield Proxy Set-up for IE (Dial-up)
For Firefox users - Tutorial - Web Shield Proxy Set-up for Firefox

Well webshield is set exactly as what you have suggested. It doesn’t happen every day but sometimes only. I will take the screen shot next time when the login window pops up.

For Windows XP/Vista, the scanning is transparent, you shouldn’t change anything… (again).

Thanx I got it now.