Hi
I'm sorry, but somehow i miss following this issue.
My apologies.
Well...If it's not GD Library support, or rewrite permissions files or memory limit, honestly i don't have any idea about the origin of this problem.
I never saw "Error 324 (net::ERR_EMPTY_RESPONSE)" been discuss on 4 years support on our forum, with the exception of that initial post from you.
I search information about this error and they all point to Chrome bug... but if so, it doesn't make any sense since it's happening on others browsers. If you "google" this issue you will see what i mean.
Anyway, besides helping you, there's all the interest to know why is this happening for future situations.
I will ask support of Dziudek - our lead developer.
Cheers