Comment # 5 on bug 936201 from Bob Goddard

If this is the same problem I am having, then from a vty, run init 3, then init
5 will allow X to be viewable again, albeit you have lost the previous desptop.

It seems to be a problem known for a few years, it affects all chipsets,
NVidia, AMD, Intel, & display managers.

It would seem there is some code that has been replicated across projects where
it ignores external displays and assumes only internal ones exist.

There are a few work arounds, but I think the only one which always works is to
force edid info to ignore the down signal, but as Suse do not distribute edid
tools and info...