my instructions are if you know which tweak caused it.

in this example we take that the tweak has modified /usr/share/themes/blanco/meegotouch/meegotouchhome/style/meegotouchhome.css

follow instructions on http://wiki.meego.com/N950/Fixing_MALF_state

follow till step 7
once rootfs is mounted,
open terminal
sudo cp -R /(path to your backed up file)/ /media/{rootfs}/usr/share/themes/blanco/meegotouch/meegotouchhome/style/
once the file is copied umount the directory following step 11 of the wiki.
then reboot and the reboot loop should be gone.

only possible on linux and not windows AFAIK.