Three debug errors Syntax error, "yui" is undefined, Portal?

When I launch My Yahoo as my home page a allways get three debug errors that I must cancel before I proceed. Line 68 Syntax Error, Line 76 "yui" is undefined, Line 756 'ymyPortalManager' is undefined. How do I fix this? I already downloaded and installed IE7 ad this problem is specific to the "My Yahoo" page only on my work computer.