MJ Registry Watcher is a simple system tray program that monitors changes to any of the startup folders, startup registry keys, and any files you want alerting on. If a trojan attempts to change your startup settings, you will be alerted, and you can prevent any changes being made.

It is fully configurable as to what keys and files are monitored, so, if you have a vested interest in protecting your file association for the mailto protocol (your default emailer), so that your preferred app loads them, and something else is trying very hard to undermine this association (Outlook for example), this will popup, offering to stop a new association attempt, after Outlook had loaded, say. The key that stores this association is hkey_lmus\software\classes\mailto\shell\open\command, and you could protect other associations by changing "mailto" to the desired type, for example, "jpegfile".