Splitting hard disk on ubuntu

[Astro9t]

Hi I just bought a new dell laptop with preinstalled ubuntu.It has 500 gb HDD.I want to install windows alongside ubuntu.To do this i tried splitting partition (493 gb ext4)using disk utility tool but it gives error "daemon is bein inhibited"

 

[bmanv13]

http://askubuntu.com/questions/51310/the-daemon-is-being-inhibited-error-message-when-mounting-volumes-on-a-partiti

Try reading the topic to see if that's exactly your problem.