Best piece of advice for the Linux newbie..
If the computer operating system is acting-up having silly troubles and glitches it means your OS caught some of the cyber diseases (malware) from the internet.. Save your recent work to a reliable flash drive (not made in china), or to an external hard drive.. Save your bookmarks, and reinstall the operating system fresh.. Now days the internet isn't safe for any OS.. The hacker-maggots can infiltrate and damage any and every OS... Last week the netbook's OS wouldn't save a new note on the desktop, so I transferred the few new files to a backup, and instantly reinstalled the OS... The hacker-maggots like to damage peoples computer word files.. It makes them feel like they are big tough-guy supermen in control of the whole world.. They don't have much control over anything else...Their deranged mummies would be so proud of them...
If you run into a permanent persistent 504, it's probably a virus, maybe reinstall the OS.. Keep in mind that there's a global war going on out there.. The kookoos war is in the internet too...
One thing I accidentally did when the computer was being pestered by a constant 504's is I changed hard drives, and in a half hour put the original hard drive back in, and the 504's vanished.. Maybe if you are bugged by a pest 504, you might try unplugging the notebook and pulling the notebook's battery for a few minutes.. Might do something..? Just guessing...
Make a secondary notebook that's used exclusively for the internet, not used for your treasured private files, editing, and archives.. Only add needed copies of backups to the netbook: pix, vids, notes, music.. copied/uploaded/backuped stuff that doesn't matter in the slightest if you lose any of it.. My crapper netbook has the installation CD always in the slot.. If something bad happens to the OS, I copy my most recent work to a flash drive, CD, or external HD, the three or four new files and a few downloads, push in the CD slot, reboot, and reinstall the OS.. So what if it takes 90-minutes... I have a hundred Linux-loaded notebook hard drives.. Should the netbook's OS get corrupted, out goes the hard drive, and in goes a new one, and I'm back on the Web in 2- minutes. The troubled hard drive goes to the utility desk to the utility notebook to have its OS DBAN'd and reinstalled...
These days it's good policy to check properties permissions before you transfer new items to the back up.. Do so check in properties that it isn't 'executable'.. If a download (pix or video) is executable, immediately delete it without opening it..
It's absolutely crucial you install the OS encrypting the installation and the home file.. If a new Linux installation ISO doesn't have those two encryption features it ain't worth 'a dead blade of grass in the lawn'.. From now on before I test a new Linux OS I'm gonna ask in their forum if the thing can be double encrypted.. If it can't, then I 'll just forget about it.. Won't waste my time downloading it...