Bug: The Multiple Ring Buffer tool fails for ArcView and ArcEditor license users
If an ArcView or ArcEditor license user tries to use the Multiple Ring Buffer tool with only one specified buffer distance, the tool fails.
In the Python Script for this tool the lines 145 - 186 are only executed when not working with an ArcInfo license. The error occurs when the script tries to complete Line 153, which defines the second input variable. When there is only one value the script tries to take x+1, which equals nothing, so the script breaks with an error.
Use the buffer tool located in ArcToolBox > Proximity > Buffer to buffer a single input. Only use the Multiple Ring Buffer if multiple inputs are to be used.