I get this as well. I can't play for very long without doing something to make the client crash, either I use a potion or go back and forth between melee and range attack.
About the "cannot effect target PC" I remember having that problem with some potions. I figured out that when I had my character targeted and used the potion I would sometimes get that message, but then I'd just hit esc lose my target and try the potion again (without any target) then it would work and the potions would be cast/used on my character anyways. try this, maybe it'll work better for you.
I'm a little vague on details and information right now, I can't give any more information until I'm back on my own computer and can specify what exactly the error says and what my computer properties are.
I expect the error has to do with downloaded files or some application I'm missing. The game ran just fine, no crashes, before things started getting changed with the new version and the latest game patch. So my RAM, processor spd, sound card... probably have very little or nothing to do with the crashes.
However, more information about the constant client crashes would be nice. I'm still using the second to latest EMU version, not the 5.2 one since I can't understand what the heck I'm suppose to do with the downloaded files (I wasn't the one who set up EQEMu with the extra downloaded files.)
Good luck to all of you, and thanks for your hard work and effort.
