I messed up my computer last week and so I'm trying to install linux on my laptop as I accidentally uninstall window 7 when I erased my hard drive. I have Ubuntu on a usb and when plugged in, but when I turn on the laptop, I keep getting PXE-E61: Media test failure, check cable and PXE-MOF: Existing Intel boot agent and Insert system disk in drive. How do I fix this? please help thank you. I have a Toshiba Portege z835-p330.