MDI mode stopped working as it was.

I'm using Axis version 2.7.11. It has worked fine and suddenly developed this problem
Now when I enter Z.1, I get an error "Linear move on line 1would exceed joint 1's negative limit.
If I enter Z -.1 I get same error.
If I enter  move on X or Y axis I get the same error. 
Manual mode works ok.
Also how does one clear the history in the MDI mode.

This sounds like a problem either with the coordinate system offsets, or with a tool offset.

Check your tool table for a spurious Y offset (joint 1 is typically Y). Though this is only likely to be the problem if you have a tool loaded and tool offsets on.

Then jog the tool to somewhere approximately mid-travel and "touch off" the coordinate system to zero in Y. Does that fix the problem?

The G10 codes can be used to set and clear offsets with a bit more precision, if needed.

My stupidity - all I had to do was re-zero the machine and hadn't done that after relocating the work.
Still wonder how to clear the history in the MDI mode. Probably clear a file - but which one and where is it.

Delete the .axis_mdi_history file or delete the contents. It's in your home directory and it starts with a dot so it's usually hidden from you unless you turn on show hidden.

JT