Before this , i downloaded beta 5 , it also had som problem , but it got solved partly by itself and partly with the help of forum members.
today i downloaded beta 6 . I did not delete beta 5 before that and beta 6 replaced it at it own without user's help.
I tried to upload the blink sketch for testing (board is Arduino UNO)
But in output it completes compilation , but after that there comes a long list of errors.
Here is a picture of error