ipmitool mc reset cold
this can clear serial console issues, or wrongly latched hardware error conditions on the front panel.
The Dell DSET utility can be used to clear the ESM logs too. To get it to run last time, I had to do:
export PATH=/sbin:/usr/sbin:$PATH rpm -e --nodeps Lib_Utils ./dell-dset-lx64-3.7.0.219.bin --ostype=RHEL6-- AlastairScobie - 14 Sep 2010