Internet Explorer 7 making a problem with the yahoo mail?

after openning the new yahoo mail beta my web browser IE 6 didnt open my mail box and after installing the new IE 7 optimized for yahoo didnt open my inbox also I tried every thing but it didt work can you please help me, also an error messege appears after closing IE 7 (The instructin at "0x6c371351" referenced memory at "0x00000004". The memory could not be "read". Click on OK to treminate the program)