[support] Drupal multi site problem

[Roger]

I have several new multi sites operating successfully however on  afresh 
multi site install this morning  themes when changed from default revert 
to black text on white background, not the Seven or Stark themes, just a 
mess up of the default.

Has anyone experienced this and what can be done to work around please

Devel module does not work as it used to a few months ago so is of no 
help here.

Help appreciated
Roger