Hi,
Three days ago wheezy began to freeze at the login prompt: no keyboard 
and often no mouse, it's a i915 laptop from asus.
I looked in newsgroups whether it might be gdm3, but lighted didn't solve 
the issue. I also looked for the xkeyboard mapping, and relaunched 
dpkg-reconfigure, but that didn't help either.
syslog is clean. 
xorg.log loads the intel sandy bridge driver correctly, also 
other stuff like vesa_drv et fbdev_drv. AT the end the server seems to 
fail going on, last message seen is: "xf86OpenConsole: cannot open /dev/tty0 
(No such file or directory)".
but tty0 exists, chmod 755 helps to launch X in recovery mode, but not 
under int2, then keyboard disappears.
I was using wheezy, plus deb-multimedia & mozilla-esr.
I upgraded and dist-upgraded to jessie, but the issue remains.
Default amd64 kernel config.
Does anyone know what might help to fix it :-)
Best regards,
Ralf