Wireless issues with ARP cache

Hey all, we had a wireless network set up for three computers in our house and one system is having a lot of trouble connecting to the internet. It says that it cannot clear the ARP Cache, and that it does not have the authority to do so.

Any ideas as to how I can change the setup to allow this computer to have better access and control? I'm completely useless when it comes to technical issues like this.

Thanks for the help,

- Ben