Re: Mepis 11 wont boot after changing to a Radeon HD 4250
You can run sgfxi alone. That way there's no extraneous cruft to work your way through. The wiki is really good for this. You can keep a Browser window open and Copy&Paste the commands in a root Konsole/Terminal. Once installed it's simply a matter of Ctrl+Alt+F1 to get to the Command Line. Login in as root. Type sgfxi and hit the Enter key. Follow the prompts. Done.
You may need to do the last part (bolded above) twice. If that's necessary type 'init 3' at the GRUB screen (without the quotes) and hit the Enter key. Login as root and type sgfxi, etc.