'm using KDE 3.1-10 distributed with RedHat9.
A tried different desktop managers but KDE is most
comfortable for using and I prefer that manager.

But I found some bugs in it.
1. When you rename file using F2 the name of the
file doesn't changes. But if you rename it again
and give other name the name you gave before applied
end the last name will be aplied the next time you
rename file and so on.
2. When I add New Item to the root menu they doesn't
appears in the menu. Nut when I add this item again It appears.
3. When I choose the Single-Click Option to open files
(Control Center->Peripherals->Mouse) and click apply button
the changes doesn't applies. That problem take place with
other options changing.

IS that a bug of my distrib or this bug have all KDE users?

1. Have you tried refreshing the screen after initially editing the filename? It could be that it is actually changing the filename but not updating the screen. Would still be a bug, none-the-less.

No such problems with KDE 3.1.2 on Slackware 9