WhenI log into my yahoo mail I get error messages about ylib_keyevt being undefined.?

I also get other ones that say I have a menu button undefined and one says I have and expected '('. Then there are lines, characters and codes. Any ideas on how to fix this? I've tried tons of stuff to fix it, updated my script debugger, scanned for adware, scanned for viruses, turned my virus software off, reinstalled it. Nothing works... help!!!!!!!!!!!