Problem after upgrading PHP from 4x to 5.1.6

[eluser]Unknown[/eluser]
I have a custom app based on CodeIgniter that was working okay until I had my server PHP upgraded to v5.1.6. Now when I try to go to to any public page or to log in to the control panel, I get a blank page. I have not been able to locate where I can change the setting to get errors reported.

Any suggestions for how to get this app working again?

[eluser]cahva[/eluser]
Display errors is probably turned to off(as it should be in production environment). Check the server's error log, you can find the cause in there.

[eluser]TWP Marketing[/eluser]
Stoelting,
Two things, check for spaces after closing php tags (they can be removed),
and
check the server error log.