I switched off my my phone, when I switched on again on the screen shows uncaught exception Index 9>=9 after that shows again app error 523 reset. PLZ help!!!

There's pretty much no diagnosing those -- they are the equivalent of the random errors in Windows for which tracing the root cause is fruitless. Basically, these are the last out in the programming code -- some event occurred for which there is no handler in the code. The fix is a code update that handles the event...but, again, knowing what the event is is pretty much impossible. So, there are a few things to try:

Sometimes, the code simply becomes corrupt and needs to be refreshed -- just like a reboot:

• Anytime random strange behavior or sluggishness creeps in, the first thing to do is a battery pop reboot. With power ON, remove the back cover and pull out the battery. Wait about a minute then replace the battery and cover. Power up and wait patiently through the long reboot -- ~5 minutes. See if things have returned to good operation. Like all computing devices, BB's suffer from memory leaks and such...with a hard reboot being the best cure (but remember it may wipe out your data to factory settings).

There might be an updated code set from the carrier -- check them via this portal:

•  http://na.blackberry.com/eng/support/downloads/download_sites.jsp

The toughest possible cause is a badly behaving app. To find it, there are a couple of options. One is to see if you can read the log file:

Go to the home screen. Hold down the alt key and type 'lglg'. (You will not see anything while you type).This will bring up the log file. Scroll down (probably many pages) untill you see a line that says 'uncaught execption'. Click on this line. The name of the app will be in the info.

The other method is to remove apps one at a time, waiting a while in between (I usually recommend a week), until the problem ceases...thereby discovering the offending app.