The issue is not with the dual boot setup.
The issue is that the open source driver (nouveau) for the graphics card (nVidia Quadro K2100M with nVidia Optimus) is causing this freezes.
To have a quick workaround I disabled nouveau and related modules like advised on this AU questionAU question and answeranswer.
/etc/modprobe.d/blacklist-nouveau.conf
blacklist nouveau
blacklist lbm-nouveau
blacklist amd76x_edac #this might not be required for x86 32 bit users.
blacklist vga16fb
blacklist rivafb
blacklist nvidiafb
blacklist rivatv
options nouveau modeset=0
alias nouveau off
alias lbm-nouveau off
Next ist to build the original nVidia driver for my graphics card and install it.
