Shoutbox

I log all my chats, and yesterday when I tried to open one of them, I got an error message that stated, "An error occurred while trying to decrypt your file. Please reboot or try again on another computer."

I restarted my computer and tried again, but received the same message. I cannot try on another computer, because the chat log files are exclusively on this computer.

Does anyone know what I can do to be able to view these conversations again?