I had issues with pages being blank.
Add Quote page blank
Add Client Page Blank
Add Invoice Not opening
Add Quotes Not opening
I am on a shared host and set this sub directory to PHP 5.3
So after some suggestions from the support here and no real error messages i just tried switching it to 5.5 in the directory folder of the install.
All working now the folder is PHP 5.5
Now i have other issues
Creating new client sends me an error page
An Error Was Encountered The action you have requested is not allowed.
Creating new quote does not save and redirect to edit quote
Same with invoice does not save and redirect to edit
I will try to set each individual folder to PHP 5.5