If you are having problems with xampp under windows, check the method you are using to connect the server to the LAN. I installed xampp on my laptop yesterday, everything seems fine: apache running, no errors, firewall turned off. Then i realized that i was using WiFi to connect my laptop to the network, so i grabbed an ethernet cable and voila! xampp running and all functional.
I still don't know why that happened. I think the router (a cheap one) is blocking communication between devices (i think its called 'user isolation' or something like that). I have seen that option in better routers and can be disabled, just not in this one haha