There is a bug in latest XAMPP Apache Distribution for Windows, which result in HTTP connection reset when accessing following menu options:
* Install/Update Languages
* Install/Activate Extensions
* Install/Activate Themes
* Install/Activate Chart of Accounts

The problem suffers at least following Apache distributions:
* XAMPP 1.7.7
* XAMPP 1.8.1

Problem here is bundling Apache and PHP5  based on two different (and incompatible) OpenSSL versions. More details you can find  in PHP bug report page.

So either you have to downgrade your XAMPP to an older version, use configure Apache to call PHP using FastCGI (instead of using mod_php), or install another Apache/PHP/MySQL distribution.

You can change to the latest WampServer 2.2. This works just like a charm.
The WampServer 2.2 uses:
Apache 2.2.22
PHP 5.4.3
Mysql 5.5.24

_________________________
/Joe