So earlier I upgraded to Plesk 11 from the latest version of 10, installed the nginx reverse proxy. Everything seemed fine, however one subdomain's software wasn't working, the customer thinking it was his cock up tried to do a restore using the backup system and then everything went to pot. Basically, every single domain got suspended, even though they were showing as active. To fix, I had to suspend every domain, then re-activate them and disable the nginx proxy to enable the customers software to work again. If theres any logs which may help you troublehshoot to fix the problem, let me know where they are and I can send them along.