First, what operating system are you on (XP, Vista, Win7)?
Are you running remotely or on the machine that the software was installed on? Solid Edge 2D Drafting will not run remotely.
I have also seen problems with UAC and installation. When you install you should install with the UAC turned off and make sure you install as administrator.
Uninstalling, turning off UAC, and installing as administrator may fix the issue. When you download the software, save it locally to your machine instead of running it directly. This way you have it in the case you need to install again.
Another thing to check for is to see if there is a system variable called SEDEMON_LICENSE_FILE or SELMD_LICENSE_FILE? ..