Omega theme not rendering correctly when css aggregation is disabled I have tried clearing the drupal caches and manually deleting the aggregated files. Also tried clearing the browser cache. 

Anyone seen this problem before?
Can be because it needs polyfills which are only loaded with aggregation turned on. 

Try with a CSS3 standards compliant browser (ie. latest version of Chrome) which would not need the polyfills at all.

Omega 4 comes with these polyfills:


Selectivizr.js
CSS3 Media Queries JS
Respond.js
CSS3 PIE
HTML5 shiv