Can't open e mails

Question

Have Mac PowerBook G 4 , OS X 10.28. Have used Opera for over a year successfully. Today screen prompted to download improved Opera software, I followed instructions. Opening inbox of my e mails" hotmail.com" looks fifferent.. now I click on incoming mail & they will not open. Bottom of page says " Statement on line 1, connot convert undefined or null to Object Backtrack".   I have another computer so can receive you reply.Ken Meeker.   [e-mail]