there might be a few items to be aware of when you are seeing this kind of behaviour.
- Your theme cache is invalid
- You have enabled debugging to developer level
- The file permissions on your moodledata are incorrect.
The solutions for these are:
- Purge your caches (Settings > Site Administration > Development > Purge all caches), this will rebuild the correct caches
- Disable full mode debugging
- Correct file permissions so that apache can read and write to these files