[CentOS] update to 5.5 small issues

a couple hours after the update (and requisite reboot and reinstallation of nvidia proprietary driver), I noticed I wasn't gettting any email. upon a little investigation, I noted that the update had replaced my custom sendmail.cf with its own. I don't recall updates to sendmail doing that previously,....

also, around that time my panels stopped unhiding, so they remained in a hidden state that I could not recover them from. logged off and on and it didn't help, in fact it was worse: no panels at all. so I did a reboot and now they seem to be working. I'll have to keep an eagle-eye on them.

so far, all else seems well.

Thanks to the whole team who makes Centos possible!