audio problem on WINDOWS 7

i have a problem...i have the last version of Win 7 x64 and everything works perfact like vista but i have one problem with the sound....i have "IDT high definition audio codec" installed on my computer and i connected it to a reciver 5.1 with a optical cable....my problem is when i play a movie on the computer its doesnt work on all the speakers like its supposed to.
u know... the sound supposed to be splitting in a diffrent way to each speaker. only FL and FR works.
on vista its was working perfact.
for those who wondering...i have installed everything (codacs for 64 bit and for 32 bit)
what i need to do?

Which sound card do you have? Or if it's onboard your motherboard, the motherboard model would help

Do the rear speakers work under any other circumstances? Also, have you tried viewing the speaker config settings to see if there are any decoding options?

Hi,i got more or less the same problem, i got realtek codecs on a GA-MA790GP-DS4H motherboard, even i have selected the right output (spdif), i can't find the of tell to the SO that my speakers are 5.1.

Is in win 7 ultimate x86


Thanks a lot