BURP wont load new page after "forward"

FIrst of all I LOVE this site, so much content and the whole thing is just amazing so props to the creators.

For the past 2 weeks whenever not at work all i do is learn modules, did some starting point machines and felt confident to try my first “real” machine which requires me to inject something with burp which has been an absolute nightmare!! I can intercept just fine but when it comes down to injecting what i need and hitting the “Forward” button inside of burp the browser just says its loading and stays that way…

I am using the pwnbox and tryed everything i could think of playing with this setting, firefox and foxyproxy and the actual burp…i never had alot of knowledge as far as the inner workings on proxies. I’ve been switching ports 8080, 8081, 8082 … spent hours researching the web before finally getting desperate enough to post this… if anybody could help me out i would greatly appreciate it because i cant pwn this machine until i can get past this step