Why am I getting this authentication window

[Venkat & Radha Venkataramanan]

Hello:   I am running Tomcat 5.0. I installed it about 2 months back and I have been learning the ropes these days.   This morning when I tried to go into the Manager application and/or the admin application (http://127.0.0.1:8080/admin/), I get an authentication box:     I don’t know why all of a sudden I get this dialog box and even if I supply a local user/password, I cannot seem to go past this.   Any help you can provide is much appreciated.   Venkat