user uid and gid change to 999999

We are having a weblogic domain running with 4 managed
servers on OEL5, on this domain we are using a linux domain user  “domusr”
provided by OID, so normally we log on to the server with our own user
  and when needed we do a su to the domain user

But recently on one server we encounter a problem that the
uid and gid for this domusr suddenly change to 9999999, this only occurs on
this one specific server and not on the other 3.

So on all 4 servers:

 

id domusr      will give
      uid=1234(domusr) gid=40000(corp_domusr)
groups=4001(dba),20001(login_server1),40000(corp_domusr)