When my virtual machine is running, it seems like my Ctrl key is held down. I want to SSH to my vm using Putty, my password has 'm' in it, but whenever I type m, the password is sent.
As far as I remember Right Ctrl is the default Host key in VirtualBox. Try changing it to some other key (for example Application key, ie. the one that opens context menu). You can do it in the VBox global settings (not VM properties).