need a little help

[lightning20]

ok so i went out yesterday and bought a home theater sytem it's not the best but but good enough for me
http://www.bestbuy.com/site/olspage....=1186004972651
well i hooked it up by hdmi from my ps3 to the reciever to my tv which is a LG model 42lb5df-ul if that helps well everytime i try and turn it on it won't show a picture unless i turn on the reciever first turn it to hdmi input 2 then turn on the ps3 then i get a picture but if i change the input to my direct tv then go back i won't get a picture again don't know whats going on. Also every now and then it will say invalid format but this has happened with my 360 before then all of a sudden the picture comes back but sometimes it won't and i have to restart the 360 to get a picture again(360 is hooked up directly to the tv). My tv supports 1080p so i don't know why it won't get the signal sometimes. thanks for your help guys