YasT on line update and software installation stoped functioning

Hi, I have the following problem but i don't now how i got it :o It seems that after a reboot the Yast Update and Install functions stoped. The following message i get from yast usr/lib/YaST2/bin/y2base: error while loading shared libraries: /usr/lib64/YaST2/plugin/libpy2ag_hwprobe.so.2: undefined symbol: hd_busid_to_hwcfg how can i resolve this problem ??? any suggestions ?? Please it is urgent! GX