One thing I've learned the hard way recently though is to be really sure of what tab you're using at what moment. Having tried a few things out in the Sloodle code on my local installation, I wanted to uninstall it from my local Moodle, and re-install it to see if my changes worked properly. Unfortunately, the Moodle tab I had open at the time wasn't the one on my local machine... but rather, the one on my web-server. I didn't realise until a fraction of a second too late!

I didn't lose any seriously important data... this time... but it was quite a nuisance anyway.

I now simply don't keep more than one Moodle open in the same instance of Firefox at the same time. It's not worth the risk!