Just got some strange errors when adding a template design and trying to view my index page.
MySource Warning
Error text not found for this code and locale [CORE0257]
array (
0 => '117',
)
PHP Warning
paint([SYSTEM_ROOT]/data/private/assets/design/114/design_file.php): failed to open stream: No such file or directory
Fatal error: paint(): Failed opening required '/home/websites/mysource_matrix/data/private/assets/design/114/design_file.php' (include_path='.:/home/websites/mysource_matrix/php_includes:/usr/local/lib/php') in /home/websites/mysource_matrix/core/assets/designs/design/design.inc on line 839
Re-running compile_locale.php won't help; I found a problem with that error code that I've just fixed (in 3.8 it will still give you an 'error not found', in 3.10.0 RC1 it will result in the wrong error…).
The error should be Cannot find the design file to print the asset, "117" which happens if it can't find a design file for a design (or customisation) or its parents. Try following the instructions Anthony gave you first, see if that helps.