Trick to clear idm completely from registry !!

1. Go to  control panel n uninstall idm software.

2. Den go to run n type regedit 

3. Now you will see registry editor

4. Go to the bottom of that you will see HKEY_LOCAL_MACHINE.

5. Click there n now u wil see SOFTWARE click here again..u wil see internet download manager        .DELETE   DIZ(internet download manager).

6. Now u can re install n use internet download manage.