Windows 7 64 bit, Intel i7
This happened to me as well after I updated the SDK to be Jelly Bean compatible. The folder platform-tools\lib was gone. I also wasn't able to uninstall/reinstall the program-tools in the SDK manager at first. It gave me the error that a particular file in the android\temp folder was not there. I had to change the permissions on the android folder to allow every action, and that solved it.