Is it bad to download stuff while copying?
 

I started doing it because SuperDuper didn't seem to have a problem with it, but now I've got some really funky errors on my system I've never seen before. I don't know if they're related, but the timing seemed coincidental.

In general, yes, it's a bad idea to download while backing up. An active download is a file that's constantly being updated, and will often fill the destination if copied...

Ok thanks that's good to know.

Two more questions:

1) Is there any particular file or preference that can get corrupted by doing that, so maybe I know what to throw out to fix my system?

2) Is it bad to use the computer in general, because *any* usage will cause files to become altered?

Thanks for the quick response!

No, no preferences will get corrupted. What'll happen is that the destination volume will fill.

In general, even when you're working, you're not constantly streaming to an open file, so it doesn't present much of a problem. But it's definitely best to leave things alone while a backup is happening. Think of it as a nice time to get a cup of coffee.