A blank screen is often an error that isn't showing. Please enable debuggin and set error reporting to maximum and see if and what error message you're getting. Also please give your system details.
Enable Debug
Backend > Site > Global Configuration > System > Debug System = Yes
Set Error Reporting to Maximum
Backend > Site > Global Configuration > Server > Error Reporting = Maximum
System Details
Backend > Help > System Info > System Info
- Database Version: e.g. 5.1.33
- PHP Version: e.g 5.2.9
- Web Server an version: e.g Apache/2.2.11 or ISS
- Web Server Operating System: Windows (e.g. the (Win32) in the web server info
- Web Server to PHP interface: apache2handler
- Joomla! Version: Joomla! 1.5.26 --> make sure this is the latest version:
http://www.joomla.org/download.html- User Agent: Mozilla/5.0 (Windows) - the browser and the operating system of the user
Memory limit
Backend > Help > System Info > PHP Information > memory_limit (e.g. 64M)