Java problem on my 6600

[synchro]

Hi!
I have a serious problem with my nokia 6600.
It's like this: I download a game or app from somewhere of the internet and tranfser it to my phone using a bluetooth connection. If the file I tranfser to my phone is a .sis file, the installation goes fine and I can strat using the app/game.
But if it is a java game the phone hangs during installation. I've tried both donwloading games and even purchased them through various services.
I've even tried restart my phone, but it still hangs with the following error msg.:"Program closed ChilInstaller!" This message comes after I've agreed to everything it ask me about. Then I have to restart the phone again. Can anyone please help me with this?
Do I need to reset or format my phone, but if i do a phone format it will be blank right? Won't that result in that I loose everything I have on my phone. (Contacts, apps, games pictures, sounds and apps installed by nokia)
Please help me

[nk_au]

Try taking out the MMC Card and startup the phone. It might be a conflict or corruption. Not sure.

If you do the three-key format (Green * 3 held during startup), you will lose everything on your Phone Memory. But you can use Infrared or Bluetooth and backup that precious data. Your Memory Card will not be touched during three-key format.

[Shafman]

If it's still not sorted, then try this post: http://nokiafree.org/forums/t63019/h&highlight=childinstaller/s.html
It should help you.