Version:           4.6 (using KDE 4.6.5) 
OS:                Linux

I am not an advanced user but I will try to explain my problem with detail.

I am connected to a router to get internet through a Ethernet cable. If the cable is connected and the router provides an IP with exit to the internet, everything is OK. If the cable is disconnected, everything is OK. The problem comes when the router provides an internal IP address but with no exit to internet: the desktop is rendered unresponsive, the taskbar does not respond, the widgets in the systray does not respond either, if I run an application it takes more time than expected to show up, etc. If in this situation, I disconnect the cable, the system is again normal.

I was able to monitor the cpu load during the situation and it stays in normal levels (ie, the unresponsiveness is not caused by an application using 100% of the cpu).

Reproducible: Always

Steps to Reproduce:
1. Connect ethernet cable to a router
2. Disable router access to the internet
3. Check behavior

Actual Results:  
-

Expected Results:  
-

Kubuntu 11.04 on 64-bits.
My system has sufficient resources and this unresponsiveness happes only when the situation explained occurs.