To be very honest, I dont know whether not flushing the cache might
cause trouble here.
I just chipped in with what little i knew :).
You could check the dev/prodn log to get a better idea of whats going
on and where things get stuck. You could also disable subdomains
temporarily and make sure it IS indeed a subdomain problem in the
first place.
But most likely, the logs will be your best friends here. You will be
able to trace the problem there the best. Do let us know what you find
there. And ill chip in what I can if I can :).
The Sites controller index action seems fine.
The image show action though, seems to search for images with weird IDs
(submenu-li and account here).
You should make sure that link is correct and the required parameters
are
passed on correctly. and the route too is generated correctly.
You might also want to get this line checked. This is probably the line
throwing the page not found error. Hope that helps.