You may got some problem when you enable the dolphin's friendly permalinks(it seems like the rewirte rule doesn't work).
I have got the same issue few days ago and it's ok now.
Here is what I did:
1.Open the httpd.conf(apache server's config file) find this "#LoadModule rewrite_module modules/mod_rewrite.so" delete the "#" to allow apache lode the rewrite_module.
2.Find the "AllowOverride None" change to "AllowOverride All".
3.Sometime may change the "Options" either.
4.Restart the apache server.