workstation service

Our workstations currently will randomly and completely unpredictably
take an hour or more to fully render the desktop icons on roaming
profiles. We've done all the usual responses to this issue and
currently the only thing which fixes it is to log onto the workstation
as local admin - do a release/renew of DHCP and log back on as the
user.

The desktop renders normally and quickly and life is good until it
happens again. Recently we discovered that flushdns whilst logged on
as local admin fixes it.

So now we are trying to determine what possible workstation/domain/
network functions could be kicked off by
either of these two commands? And what of these functions the two
commands have in common?