Using Xampp V 3.2.1
I didn't find this version at http://sourceforge.net/projects/xampp/files/XAMPP%20Windows/

I installed xampp setup from below mentioned link
https://www.apachefriends.org/download.html

and xampp-win32-5.5.24-0-VC11-installer.exe setup is installed.

Xampp.png (33,072 bytes)   

Xampp.png (33,072 bytes)   

I was not able to reproduce your problem with a fresh install of 1.2.19 using xampp-win32-5.5.24-0-VC11-installer.exe.

You have to provide step by step guide how to reproduce the issue from scratch.

As you stated,I just installed mantisbt 1.2.19 using xampp-win32-5.5.24-0-VC11-installer.exe on fresh system to provide you actual steps but failed to reproduce this situation.But this situation still there on first installed system.

viz,

This is not a bug or feature request for MantisBT (you are asking for help on how to deal with an issue that can't be reproduced on a clean installaion). I am therefore resolving this issue as "no change required".

Feel free to reopen the issue if you can provide step by step guide to reproduce the issue.

Please use the forums, the mantisbt-help mailing list or IRC to get support on customizing and using MantisBT (refer to http://www.mantisbt.org/support.php for links and further details).

The following steps might help to find the root cause of your problem:

1. temporarily configure your system as follows:

$g_display_errors = array(
E_WARNING => 'halt',
E_NOTICE => 'halt',
E_USER_ERROR => 'halt',
E_USER_WARNING => 'halt',
E_USER_NOTICE => 'halt'
);
$g_show_detailed_errors = ON;

WARNING - SECURITY RISK: the 'show_detailed_errors' config can cause MantisBT to display sensitive information about your system. We recommend to restrict its activation to a Test environment, only for as long as necessary. If possible, do not turn it ON globally, instead limit it for specific user(s) using the Manage Configuration page.

2. Reproduce the error

Maybe the output does help you to resolve the issue

Check also your Apache and PHP logs for errors and warnings.