Version:           unspecified (using KDE 4.4.4) 
OS:                Linux

This happens to me consinstently after some hours of use plasma:

 * plasma is not showing icons any more on the panel or in the desktop folder but they are there, I can click them
 * I get "The process for the file protocol died unexpectedly" on every attempt to open File dialogue or tab in Dolphin
 * the .xsession-errors is *full* of these lines:
plasma-desktop(2833): Failed to lock file "/var/tmp/kdecache-dusty/kpc/kde-icon-cache.lock" , last result = 1
plasma-desktop(2833): Failed to lock file "/var/tmp/kdecache-dusty/kpc/plasma_theme_default.lock" , last result = 2
plasma-desktop(2833) KIO::SlavePrivate::SlavePrivate: Connection server not listening, could not connect
kdeinit4: preparing to launch /usr/lib/kde4/kio_file.so
kio_file(29752)/kio (KIOConnection) KIO::Connection::connectToRemote: Unknown requested KIO::Connection protocol=' "" ' ( "" )

Another consequence of that problem is that the watch/calendar applet on the panel shows me the GMT time instead of the local time

Reproducible: Always

Steps to Reproduce:
On my deskstop:
- login
- use the desktop for some hours (sometime days)


Actual Results:  
half broken panel