it might help to know your mother board.
if you have two of exactly the same drivers then remove one for sure.
be carefull tho somethings have similar names when it comes to installed dlls.
is there a flashable rom in your motherboard that might increase the BIOS features or correct mistakes int he BIOS.?
is there a way you can try another simple sound card against the Cmedia 5.1 and see if there is an echo.
In your volume control panel do you have any extra features that might be similar to Audigy re: listen live., this might be causing an echo.
in dxdiag does your sound play with the test.?
Did you remove some drivers using safe mode?
If no-one gives your an answer to a question you have asked, consider:- Is your question clear.- Did you ask nicely.- Are you showing any effort to solve the problem yourself 