I have installed JMS 1.2.78 with Joomla 1.5.23 :

After installation , and registration we get blank page for following 3 sections:

Manage Sites
Templates
Tools

Rest of the links like Settings, Layout, About us etc are coming up perfectly fine.

php.ini configuration is same as guided in the installation tutorials.

access_logs are reporting Http 200 for pages which are coming up blank.

How can we resolve this blank page issue.

Tried installing the component on other environment as well and facing same issue.

What is the root cause? How this can be resolved?

If you have a blank page, this is the symptom of a PHP fatal error.
So check your "error log" file to get more info on the error.

I suspect that you have a file permission error somewhere.
To know where, you need to read your "error log" file that will give you the info.