Michael said he would do more testing.
Did you chmod both config files? I know if you dont chmod the config-int.php file you can get a white page on some servers.
Some more information exact steps of what your doing would help as many Classifieds install works fine for me and I have done quite a few since 2.1 came out. Hard part about support is I am not there to know what the user is doing. Yes I helped angler by stating fixes for errors he was having to do things manually as it would have taken way longer trying to diagnose what he was doing different upon an install than I am.
I think personally the issue here is you did not chmod the second config file as that makes sense.