Kaktussoft said:
Language packs can be installed on Windows 7 Professional/Ultimate only... so they did a fancy trick.
Do this [link removed] so install the Czech language pack again using Vistalizator. Maybe uninstall language pack first (?)
Kaktussoft said:
You better "remove language" Czech using Vistalizator - change display language in Windows Vista and Windows 7
First a correction: Language packs can not be installed on Professional. They are exclusively for Ultimate and Enterprise editions.

   Warning
Using Vistalizator or any other language crack can cause severe problems. Please read these posts before trying / installing them:

Kari