How can I fix the update translation?

[Presta1.5.4.1Newbies]

It happens almost every time after I have tried to update translation manually.

 Request denied by WatchGuard HTTP proxy.

Reason: IPS matched signature "WEB-MISC Hashtable Collisions", id='1056078'

Method: POST
Host: grandcoralaustralia.com.au
Path: /psadmin/index.php?controller=AdminTranslations&submitTranslationsFront=1&token=01845ab57e5b86d522b71172534cf81

First resolution : delete language then add new under the localization > not work and the image thumbnail has lost.

Second resolution : I tried to solve the problem by importing language pack manually > not work.

 

 

Any idea please.

 

[Presta1.5.4.1Newbies]

More to add my prestashop version 1.5.4.1 and English is the default language. 

Existing problem is login section is in Thai while the selected language is English