Hello,
The issue is related to a server security feature ; you can reproduce the problem even in the demo website.
The HikaShop team will investigate.
In the meantime you can access the documentation via the regular website link :
www.hikashop.com/support/documentation.html
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.