I just tried to transfer a sample file from ALCF to OLCF by running globus-url-copy directly on dtn01.ccs.ornl.gov and am getting the same errors intermittently.  Here's the output from my test:

-bash-3.2$ whoami
childers
-bash-3.2$ hostname
dtn01.ccs.ornl.gov
-bash-3.2$ grid-proxy-info
subject  : /DC=org/DC=doegrids/OU=People/CN=Lisa C Childers 319818/CN=1265754967/CN=849672331/CN=1092164783
issuer   : /DC=org/DC=doegrids/OU=People/CN=Lisa C Childers 319818/CN=1265754967/CN=849672331
identity : /DC=org/DC=doegrids/OU=People/CN=Lisa C Childers 319818
type     : RFC 3820 compliant impersonation proxy
strength : 1024 bits
path     : /tmp/x509up_u3947
timeleft : 11:51:30
-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:02 UTC 2010
-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:07 UTC 2010
-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:12 UTC 2010

error: globus_ftp_client: the server responded with an error
500 500-Command failed. : globus_l_gfs_file_open failed.
500-globus_xio: Unable to open file //lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
500-globus_xio: System error in open: Permission denied
500-globus_xio: A system call failed: Permission denied
500-
500 End.

-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:23 UTC 2010
-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:28 UTC 2010
-bash-3.2$ date -u; globus-url-copy gsiftp://gs1.intrepid.alcf.anl.gov:2811//intrepid-fs0/users/childers/persistent/datasrc/sdata/100Kfiles200M/2-1Kfiles200M/cf1-604-200M gsiftp://dtn01.ccs.ornl.gov:2811//lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
Tue May 11 21:34:35 UTC 2010

error: globus_ftp_client: the server responded with an error
500 500-Command failed. : globus_l_gfs_file_open failed.
500-globus_xio: Unable to open file //lustre/widow1/proj/csc024/childers/ddest/multi/cdc3/100Kfiles200M/2-1Kfiles200M/cf1-604-200M
500-globus_xio: System error in open: Permission denied
500-globus_xio: A system call failed: Permission denied
500-
500 End.

-bash-3.2$