I have purchased IDM but still get the following message: "Internet Download Manager has been registered with a fake Serial Number or the Serial Number has been blocked....". What should I do?
After entering serial number just exit IDM using "Tasks→Exit" main menu item and then start it again:
If it does not help, please download and install the latest version of IDM:
Download Internet Download Manager (10 MB)
In any case it is better to reinstall IDM for you, because before you most probably have been using a version modified with a crack.
If it does not help, please try to delete the following registry keys:
Open Regedit and search for them using F3.
Please read how to work with registry.
If you cannot delete a registry key, you need to right click on it in RegEdit and do something with it owner. You may search in Internet for something like 'cannot delete windows registry key permissions access'. For example: try this link
Then try to register IDM with your serial number again.