Thank you so much for answering - then I will leave the css-files.
I already tried yesterday to put the code: define('WP_MEMORY_LIMIT', '64M'); into my wp-config.php - but I still get the "High memory usage notification" mails in my inbox every time i log in to my WP dashboard.
I contacted my host and they say the PHP limit is 128MB.
I still suspect it has something to do with some upgrading. The thing is I have Backupbuddy and after i upgraded WP and one plugin (pronamic-google-maps) - the backup I do is suddenly more than the double size (from 67,23MB to 176,82MB). Thats why I suspect to have some duplicate files somewhere.
Now I tried to deactivate the pronamic plugin. But I still get the errors and High memory usage mails.
By the way my dashboard looks exactly the same after upgrading to WP 3.1.3 - maybe it's a stupid information to give - but I'm trying hard to figure out where things went wrong.
Could you tell me - is there a difference between WP-Memory-Limit and PHP-Memory-Limit?
Thank you again.