Hii Friends

Whenever i try to import contact.csv on my sugarcrm (i.e. http://www.mysite.com/mycrm ) i got one error :
On Firefox it ask me to download "index.php" in place of importing my contacts
and
On IE it gives 403 forbidden error
Friends now a days i am using ubuntu as my operating system and this is first time when i face such kind of error
i already try to import from windows operating system but problem remains same so i feel i am missing something at sugarcrm end.

Do anyone have any solution for this kind of problem.
i do not understand why this happen as i install sugarcrm properly and able to import contacts till yesterday.

Plz help me if u can.

Thanks in Advance

Aditya