Internal server error in suitecrm

Many times suitecrm gives 500 internal server error, and gives blank page,
While sorting in listview also it gives 500 error.
while creating new entry in suitecrm also gives 500 error,
We tried to capture cause of issue by turning developer mode on but it does not provide any fatal error or error which can stop exexution.

Could you please provide your assistance to solve this problem ?

Before we can offer any assistance we need to know:

SuiteCRM version
Server operating system and version
PHP version
Database type and version

If you can provide those details then at least we have something to work with.