No matter what I do, Helm logs me out - either straight after logging in, or after I try to access anything within the control panel.
1.) Make sure cookies are enabled on your web browser. Open up a browser and go to Tools > Internet Options. Choose the Settings button and in the new window, make sure "Automatically" is selected. Choose OK.
a.) If this doesn't fix it, open the Helm Configuration Tool. Go to the Control Panel Website tab and uncheck the "Create a website..." box. Then click Apply. This will remove the Helm website from IIS.
b.) Now check the "Create a website..." box again. Click apply. This will recreate the Helm website. Try and log in again now.
If you still have issues, there is a good chance that there is something wrong with IIS - it would be a good idea to reinstall IIS.