I didn't have exactly the same problem, but you can check this:
To check if mod_rewrite is activated go to routeyourforum/admin.php?tools/phpinfo.php it will be shown your PHP configuration, then find the loaded modules at Configuration apache2handlerI've checked and doubled-checked points 1 and 2.
On point 3, the urls to change--they just don't lead anywhere. Could this be an indication that mod_rewrite isn't installed?
The mod_rewrite feature is enabled on our shared servers. As for AllowOverride, there are some settings that can be overridden. What are you trying to override or install that needs this feature? With that info we can check our server to see if it fits your needs.
If you have any questions or comments please let us know.