Hi, I hope this will work for you, because it worked for me.. this problem almost made me go crazy, but here is my solution...
Simply go to your WINDOWS folder, from there to the system32 folder. There you should find a file named nvopenal.dll, copy it away.. (or delete it but it's safer this way..) Then go to
http://developer.creative.com/article....&aid=46
download and install the latest open Al version..
then Arma should start! Hopefully this worked for you!
(If OpenAl won't install and say that it's already in use, or something like that, don't remember what it said anymore.. anyway, there is a solution to it.. If I remember correctly you have to go to the system32 folder and rename the file OpenAL32.dll to OpenAL32.old and then rename the OpenAL32.new file to OpenAL32.dll. That should do it. But a word of warning tough, I'm no expert, I found it on the web so if you make backups or verify that this works.)
