The issue of disappearing icons is documented in the KDE bug tracker. The comments section of the report is rather long as the reason for this appears to be nontrivial (anything from memory corruption to compiler bugs is guessed). The issue only occurs on a desktop that is configured with "Folder View" layout and not with the default "Default Desktop" layout. After boot the file icons tend to be missing sometimes from the desktop.
A workaround to restore the icons after boot is to set the desktop layout to "Default Desktop" and then back to "Folder View". This has to be done after almost each boot and is very annoying.
The solution is to apply the patch from the commit that finally fixed the issue in KDE. Or to wait until KDE 4.14.2 is available for your distribution and then install it.
Fixing on Slackware
Slackware 14.1 contains KDE 4.10.5. Slackware-current contains 4.14.3 (as of 2015-05-27). This means that installing -current will fix the issue. However, if you do not dare to use -current, the existing KDE version can be patched. The following guide works for the 64-bit version but can be adopted for the 32-bit version too.
Firstly download the original source:
tar -xf kde-baseapps-4.10.5.tar.xz
Go into the package directory and create
cd kde-baseapps-4.10.5 mkdir build
Go into the
build directory and generate Makefile:
cd build cmake ../
Build the package:
dest directory and install into it:
mkdir dest make install DESTDIR=dest
Now you should have new binary library for folderview:
If so, then switch to root and replace the old one with it (while making a backup first):
su mv /usr/lib64/kde4/plasma_applet_folderview.so /usr/lib64/kde4/plasma_applet_folderview.old.so mv dest/usr/local/lib64/kde4/plasma_applet_folderview.so /usr/lib64/kde4/plasma_applet_folderview.so
And fix permissions:
chown root:root /usr/lib64/kde4/plasma_applet_folderview.so chmod +r /usr/lib64/kde4/plasma_applet_folderview.so
A proper way would be rebuilding the kde-baseapps Slackware package but digging in KDE SlackBuild script indicated that a large part of KDE would have to be rebuilt for that.
The Slackware 15 would contain the fix as the KDE version already in the Slackware-current contains the patch. However, the release date of Slackware 15 is not exactly known yet (could be somewhere around the September or November of 2015).