Unable to modify initial primitive mesh object settings in Object Mode.

Platform: Windows 8.1. 64 bit
Blender version: 2.69 (2.69.0 r60995)

Problem Description:
Whilst adding new primitive mesh objects in Object Mode, “Add Circle/Cube,…” Panel options (Vertices, Radius, Fill Type etc.) in the 3D Editor Tools Panel are all greyed out i.e. not modifiable. Hence I am unable to modify initial object geometry settings. The problem only exists whilst adding primitives in Object Mode.

I have not - at least intentionally - changed User Preferences / Settings lately. Nor have I added any new addons lately.

Prior to reverting back to earlier backed up User Preferences / Defaults, I’d like to know if anyone can come up with a solution. Perhaps I have accidentally swithced on some sort of a lock or something of that nature?

Try restarting blenderr
Try File / Load Factory Settings, Ctrl+U to save as default, the restart.

Thanks for your prompt reply.

Just first wanted to see if I could locate the cause but I couldn’t. So did just that. Factory Settings, Ctrl_U and reapplied a saved user theme preset.