SuSE 9.0 - useradd acting strange

I have a server running SuSE 9.0 where I have to add users from time to time. The /usr/sbin/useradd executable is acting very strange on this server -- it runs for a very long time (2-3 minutes), the cpu usage of the process is always close to 100%, and memory consumption keeps rising (to about 2GB!) until it finishes. No errors or warnings are issued, and to stop it before it exits by itself, I have to use 'kill -9 <pid>', in which case /etc/passwd is not modified. If I let it run until finished, everything seems to be in order, ie. the user has been added. Any ideas what could cause this kind of behaviour? Could the passwd or shadow files be corrupted somehow? Any tools I could use to find out? -- Lars Haugseth