[eluser]AgentPhoenix[/eluser]
@zEsHaN
After I posted the message, I started writing some stuff down about when and where it's happening. The where is pretty random as is the when, but it dawned on me that I've only ever had this issue on XAMPP. I told some of my testers to keep an eye for the issue and none of them have seen it, so it's possible this is just a problem with XAMPP. I'll try to reproduce the problem on a live server.
@TheFuzzy0ne
I'm using CI's built-in session library and storing everything in the database, so none of those should be issues. I'm storing slashes, but not backslashes.
Thanks for the responses, folks! I'll dig a little more and see what I can come up with.