Bug 6207843 picked up this SDN comment:

    Comment added by (###@###.###) :
    Please reopen; seeing this with 1.4.2_04-b05. Truss reveals that JVM crashes after attempting to unlink /tmp/hsperfdata_root after the Weblogic changes the effective user and group id of the JVM.

I think that's unrelated to 6207843, except that it apparently fails with the same Error ID (os.cpp, 751). I'm filing this bug so I can post a comment on SDN to forward people with this problem here.

I see there is also a bug 6223888 about serviceability issues with changing the user and group id of a process. This might be a related issue.