Andy
> ...so if I have to roll back PHP, I'd like to know how to go about it.
I don't know what version you had installed previously or what version sme & other related contribs/rpms you have installed so these comments are general.
View the update script you last used and basically follow the reverse order of things using
rpm -e packagename (without numbers)
to uninstall newer or unwanted packages.
Where you would be going back to an earlier version of php then follow (manually) the earlier update scripts here
http://mirror.contribs.org/smeserver/contribs/ergozd/scripts/You would use something like
rpm -Uvh -oldpackage php-4.3.10-3eo.i386.rpm
to replace the newer php with the older php, depending on which version you are going back to.
Same for other rpms you would be "downgrading" as required in the script.
As a guide I have
php-4.3.10-1db_rh73
installed and all mail systems work OK.
When you want to upgrade a live system, it's better to try a practice run on a test server to see if anything breaks. That way you don't get into problems with the production box ie you solve any problems first on the test server.
php upgrades are non standard upgrades and you do them at your own risk. While ergozd scripts appear to be good, the upgrade can't be guaranteed to work on every server, for various reasons.