hi friend ,
as your mobile freezes on installing 3-4 applications
in your mobile
it may be because the mobile internal memory is low so it
hangs or freezes.....
so when you install one application try to
transfer it to the SD CARD if possible and then download
another application from the market and again transfer it to the sd card
by this the phone memory is free and the mobile will work good....
you must maintain your mobiles free memory
between 10-15 MB if you are doing this your mobile never freezes....
best of luck....