Is it correct that libkformulalib.so in 4.1.69 has only this naming? Whithout libkformulalib.so.x and libkformulalib.so.x.x.
Also, as I undestood, it conflicts whith koffice.

Fedora user.

libkformula.so in my self compiled installation also has libkformula.so.4.2.0 and all other shorter variants ( so.4, so.4.2 ) present as well. I would recommend updating your installation. If this issue still persists, try rebooting, then contacting the Fedora KDE 4.2 package maintainers.

It was compiled from sources.
Yes, I hadn't said it before, the problem disapperied some time later, more then an month ago.

About conflict with koffice I can't say anything right now.

If you are no longer affected by this issue, could you please add [SOLVED] to the beginning of the thread subject? Thanks in advance.

libkformulalib.so still exist both in koffice and kdelibs. So, resolved status is beforehand.

Which version of KOffice are you using? You need to use version 2 with KDE 4. If you wish to use KOffice 1.x then you will need to install it in a different prefix ( /opt/kde3 for instance, along with your KDE 3 install )