I use my old G4 for pretty much everything too, and I'm still on 10.3.9.
It actually works pretty well. I'm very careful about what gets "updated".
You might take a look at
this page. It looks like 7.1.1 was never tested with 10.4.11, and therefore is not officially qualified with that OS. That doesn't necessarily mean it won't work, but as far as Digi is concerned you are on your own with that config if you have problems. You should try running the prebinding script linked to on that page to see if it solves your problem.
In the future to save yourself time, and frustration always backup your known-good system so you can restore it should some "update" go wrong. It's a good idea to keep redundant offline backups of critical data anyway since you never know when trouble will strike. It's usually at the worst possible time.