@ninthace
...It was slow to respond to loading overlays or different maps always giving an "application not responding" that did not clear until the mouse had been clicked several times...
Assuming you are running MM on a PC, which exact version, and do you have all your routes loaded simultaneously?.
I've occasionally helped people with MM issues since 2004 and this one has come up quite often. Having all your routes loaded in one Overlay would seem logical and convenient, but is the absolute worst way of working in MM. One guy had around 200 routes with hundreds, or even thousands in a few cases, of waypoints in each, over 250,000 waypoints - and that's without the Marks. For some operations, including in some cases the initial overlay load I think, MM needs to access every single one of them, hence the delay.
I divide my routes into groups and only load one at a time, so I have the route I'm working on and maybe 3 or 4 others.
Then there was the notorious 'printersettings' file in the Map Overlays directory that sometimes became corrupt.
I always advised people to close MM, rename that directory then load MM with a clean slate to see if the problem persisted.
That specific grey screen problem has also occurred before, but I couldn't reproduce it on my system, hence I couldn't debug it.
@Glyno
...Also, getting the exact area you want to print can be a bit trial and error...
I normally print at 1:25000 and just drag the red print rectangle to the exact position I want over the map. Again assuming a PC, is this not adequate for your purpose?.