How to fix castle.dll "A debugger has been found running in your system. Please, unload it from memory and restart your program."?

I was sitting one afternoon at 15:07 (Moscow time), and decided to go to Austiblox (the revival of Roblox that begins with the 2010 version and ends with the 2015 version), and abruptly bang! Castle.dll (the anti-cheat library of the old Roblox) returned the message "A debugger has been found running in your system. Please, unload it from memory and restart your program."! So how do I fix this?