Thanks for your quick response.
When it's blank, nothing will show on the page.
The PHP codes are same for all topics. Not sure why only some topics are having the issue.
I have tried to deactivate them, and even deleted all the blocks. Didn't work.
Uninstall is also returning a blank page. No errors
I have tried many things to fix the issues. One of them is to install a new SMF and copy only the boards, categories, topics, messages and user data tables. It fixed the issue. I can go with from here and update rest of the forum settings.
But I also tried to keep all data on the old forum, and just replaced the Settings table from the new forum. It worked as well. This is a better choose as I don't have to update other forum settings. Then I came to an idea to compare the Settings table from old and new installation. Then where I found if I remove the TP related parts from the settings the issue is resolved. But the mod is still there. That is why I wanted to uninstall it. I can leave it but don't want keep an mode that is not used.