Unknown Error (-54) ?

Okay so I've done A LOT of research and there never seems to be a direct cause for this error. I've tried EVERYTHING from authorizing my computer, unchecking the Read Only in the iTunes properties for the folder, Unlocking all of my 2500+ songs, restoring my iphone, updating itunes, updating my iphone, updating my PC laptop, ect.

Plus, I haven't seen people talk about it, but for me at least this error seems to be messing up a lot of my files.
For example, I have a playlist I've created called "Hep". When I plug in my iphone and get the error, some songs are missing from the playlist, and it creates a second playlist called "Hep 1" This continues every time i plug in my phone and adds, "Hep 2" , "Hep 3" , ect.

As for syncing the music, it'll only sync a certain amount of songs, and stop. When i sync it again different songs are synced and ones that were previously synced are gone from the phone.

I am so frustrated and I just want to know WHY this is happening and HOW to fix. Please and thank you for your time. xx