I can received but can’t SEND MAIL

Everytime I intend to reply e-mail or even trying compose mail, I always received the following error page:

Line: 538
Char: 50
Error: expected ‘)’
Code: 0
URL:http://us.f1518.mail.yahoo.com/ym/compose?YY=55859

Line: 325
Char: 8
Error: ‘RTEIDGenerator’is undefined
Code: 0
URL:http://aa.f613.mail.yahoo.com/ym/compose?YY=55859

Line: 2935
Char: 3
Error: ‘RTEEeditor’is undefined
Code: 0
URL:http://aa.f613.mail.yahoo.com/ym/compose?YY=55859

Line: 1857
Char: 6
Error: ‘editor’is null or not an object
Code: 0
URL:http://aa.f613.mail.yahoo.com/ym/compose?YY=55859

These errors cause me not to send or compose any mail.

Please help.

Thanks