conflicting lock issue with creating depot

[EricStar]

I am building my software, when creating depot, I sometimes(sporadically occurs) encounter conflicting lock issue, here exacted from log:

======= 11/12/09 22:53:47 PDT BEGIN swpackage SESSION

* Session started for user "root@rp3440-1.engba.symantec.com".

* Source: rp3440-1:./tmp.psf
* Target: rp3440-1:../../depot
* Software selections:
*


* Beginning Selection Phase.
* Reading the Product Specification File (PSF) "./tmp.psf".
* Reading the product "VRTScavf" at line 26.
* Reading the fileset "VXFS-CFS-AGENTS" at line 48.
* Reading the fileset "VXFS-CVM-AGENTS" at line 83.
* Reading the fileset "VXFS-CFS-ADM-CMD" at line 155.
* Reading the fileset "VXFS-CFS-ADM-ENG" at line 191.

ERROR: Cannot lock "../../depot" because another command holds a
conflicting lock. The process id of that command is 0.
ERROR: Cannot read the target "../../depot".

======= 11/12/09 22:53:48 PDT END swpackage SESSION

My build environment is:
server: HP-PARISC B.11.11 U 9000/800
And the build location is mounted to an SFS server through NFS.
SFS server is based on Suse 9, and export option to HP server is "rw,insecure,insecure_locks,no_subtree_check,no_root_squash"

Have you any idea on how this happens? It does not necessarily occurs everytime. But it did occur now and then.

Thanks very much!