.desktop file has no 'Type=' entry

good day all, I'm currently using KDE 4.5.95(RC2) I don't know when it happens or why, but after a while when I click an application icon in my panel to start for example firefox, i get a window popup saying... The desktop entry file /usr/share/applications/mozilla-firefox.desktop has no Type=... entry and the app doesn't start. when i first start kde everything is fine, and then I could go out for an hour or so, then when i get back this happens, I don't know when it starts happening. to fix it i can just kill and restart plasma-desktop and this will sort it out, but after an unknown period of time, it will happen again this has been like this for the last couple of releases also. I wonder if anyone else experiences this and how it can fixed Thanks Martin