Setting the language for non-unicode programs
Problems can occur running the installer or a content patch when a user has special characters (e.g. Cyrillic, Chinese, Japanese etc.) in either folder or usernames, but haven‘t configured their machines correctly to compensate.
The character set the installer can use is entirely dependent on the 'Language for Non-Unicode Programs' setting the 'Control Panel > Regional' and 'Language Settings > Advanced' tab. If there are cyrillic characters in the folder name for instance, and „Russian“ is not set in the „Language for Non-Unicode Programs“ the patcher will either fail to load if the cyrillic folder name is in the path of the cache folder, or fail to see the EVE install altogether if the cyrillic character is the folder name for the EVE path itself.
This goes as well for the other languages containing special characters as well (Chinese, Japanese, etc.).