Today I faced the Problem, that I was not able to select a boot Image, when importing Drivers to System Center 2012 Configuration Manager:

I double checked my permission, but was sure I’m still a Full Administrator. I was checking the properties of the boot Image directly, and some Tabs were read-only some others not:

To make them writeable again, and that you are able to add new Drivers to the boot Image, go to the Images tab of the boot Image, and click on Reload:

Read the message carefully, and accept it by a click on OK:

Close the property window of the boot Image by clicking on OK, and open it again, you will be now able to modify the Image again.

Hope this helps,
Martin