The job triggers, syncs the SCM changes and then fails because it is "Unable to delete C:\hudson\jobs\jobname\config.xml"
This happens regularly and is a real pain. We do have extensive reads via the API (javascript) as we have browser slide shows showing the status among other things in a looping javascript html-page. We have experienced the issue since at least November 2009 and thought that it was due to our setup. But since then we have changed tomcat version, made sure that we close connections from javascript and changed http server.

Started by an SCM change
Building on master
Using master perforce client: XXX_devel_interim
[workspace] $ "C:\Program Files\Perforce\p4.exe" workspace -o XXX_devel_interim
Last sync'd change: 161630
[workspace] $ "C:\Program Files\Perforce\p4.exe" counter change
[workspace] $ "C:\Program Files\Perforce\p4.exe" -s changes //XXX_devel_interim/...@161631,@161632
[workspace] $ "C:\Program Files\Perforce\p4.exe" describe -s 161632
...
Unable to delete C:\hudson\jobs\XXX_devel_interim\config.xml
Sending e-mails to: user@company.com
Finished: FAILURE