Error Console repeatedly pops up..!!

[RajThilak]

A window(Error Console) pops up very frequently whenever I use internet browser(Opera)... Its causing great disturbance for me while browsing net.. Could u pl give me a solution @ the earliest..

The following are some of the contents in that window..


Mail and chat
jayit83@gmail.com
Error from server: -ERR [SYS/PERM] Your account is not enabled for POP access. Please visit your Gmail settings page and enable your account for POP access.. Did you change your password?

JavaScript
Unknown thread
Opera has modified the JavaScript on in.f370.mail.yahoo.com (server-side browser sniffing prevents "try beta" link from appearing in old mail). See browser.js for details

CSS - http://l.yimg.com/us.js.yimg.com/lib/pim/r/medici/16_11/mail/us/mail_plum_all.css
Linked-in stylesheet
Expected ruleset
Line 611:
  #C1C1C1;}1;}#optionsnav li:hover{background-color:#E6E6E6;border-color:#C1C1C1;}
  --------------------------------------------------------------------------------^
CSS - http://l.yimg.com/us.js.yimg.com/lib/pim/r/medici/16_11/mail/us/mail_plum_all.css
Linked-in stylesheet
-moz-box-sizing is an unknown property
Line 732:
  #6f326a;background-color:#F6F6F6;cursor:default;overflow:hidden;-moz-box-sizing:
  --------------------------------------------------------------------------------^




Thanking u ..