I have the same problem on my installation on
http://helden2.deswahnsinns.de - whereby
http://helden2.deswahnsinns.de/index.php works fine.
It looks like your rewrite code has some problems, if no special file is requested. Maybe the reason is, that I use subdomains and no subdirectories?
Calling
http://helden2.deswahnsinns.de directly, produces some error in the apache logfile:
[Wed Oct 03 10:17:46 2007] [error] [client xx.xx.xx.xx] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.
Using LogLevel debug in the httpd.conf:
[Wed Oct 03 10:20:45 2007] [error] [client xx.xx.xx.xx] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.
[Wed Oct 03 10:20:45 2007] [debug] core.c(3027): [client xx.xx.xx.xx] r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /local/htdocs/deswahnsinns.de/helden2/index.php
[Wed Oct 03 10:20:45 2007] [debug] core.c(3033): [client xx.xx.xx.xx] redirected from r->uri = /
I had this problem starting from the first beta version until now. Using Apache/2.2.3 (Debian) with coresponding mod_rewrite module, PHP/4.4.6-2 (which should not matter)
If you need further information or testing, please let me know
Edit: fixed typo in "quote"-tags