ORA-12154: TNS:could not resolve the connect identifier specified or ORA-6413: Connection not open

Hi,
Am using Windows 7 64bit OS am faceed the below problem .

Error:-
ORA-12154: TNS:could not resolve the connect identifier specified
        or

     ORA-6413: Connection not open.

 

Solution:-

64-bit Microsoft OS's install 32-bit applications into the following location 
 C:\Program Files (x86)\QuestSoftware\Toad for Oracle 10.6   this is my installation Directory so i ll changed to 
C:\Program Files\QuestSoftware\Toad for Oracle 10.6   then my problem is resolved