Pokemon Soul Silver problem?

I wanted to play soul sliver game so decided to download it at rom-freak but it was fake rom, next i went to filecrop luckily i found one rom, downloaded, played it on no$gba.... everything works fine but after i tell my name to pro.Oak and minimized to little as usual, the screen turns black, sound is coming but no game i can see. I tried it with no$zoomer but results were same. Can you guys tell me how to fix this problem or the site where soul silver rom actually works without any problem...please help, this is annoying!!!