When trying to open Dolphin, it takes an extremely long time (minutes). I looked at the console output, and it seems to be nepomuk causing problems:

"/usr/bin/dolphin(19201)" Soprano: "org.freedesktop.DBus.Error.NoReply - Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken." Dolphin freezes when I open it.

I have the same problem with Gwenview. I als get the same message with strigi in the semantic desktop KCM module. It says nepomuk is working fine, though.

Dolphin and gwenview start up instantly when nepomuk is disabled.

Any idea what might be going on?

I am using KDE 4.7 beta 1 with openSUSE 11.4.

You should check if NepomukServer is running and that if it did not hang (I got a couple of issues like that, although hard to reproduce). If it is there, try to quit it (either via qdbus or killing it if it doesn't respond) and restarting it, then check whetther the problem still persists.

Another thing to check for is high CPU usage by "virtuoso-t", or a lack of this process running on your system. If this problem persists, it may be a good idea to look in ~/.xsession-errors for reasons why it would be crashing or failing to start. Removing it's databases could also be another option.

I've seen timeoouts on this from time to time when indexing was enabled, but not when it was disabled.