I removed Windows 7 and installed Ubuntu Server 12.04, but when the computer starts a black screen for Windows Boot Manager appears that looks like this:
Windows Boot Manager
Windows failed to start. A recent hardware or software change might be the cause. To fix the problem: 1. Insert your Windows installation disc and restart your computer. 2. Choose your language settings, and then click "Next." 3. Click "repair your computer." If you don't have this disc, contact your system administrator or computer manufacturer for assistance. Status: 0xc0000225 Info: The boot selection failed because a required device is inaccessible.
I want to remove it and I don't know how to do it.