Hi guys,

I am hoping someone can help; prior to this, I have tried resetting AutoCAD, all palletes and all settings to no avail.

When working on my project, I zoom in, and I draw lines but when I try to either intersect lines, trim or anything of the like, AutoCAD simply doesnt co-operate. I have the correct modes turned on in the pallette. When I try to trim especially, it tells me the lines dont intersect when they quite clearly do ( I have the correct lines selected at this point). When I zoom out far enough that I cannot see what Im working on, the line snaps, intersections, ortho modes appear to work, but I cannot locate them precisely enough due to my view.  I really need help with this since Im trying to finalise my architecture project for the year. 

If it helps anybody at all, my cursor has changed from the original white one to a usc one which I dont like using. Furthermore, Next to my cursor appears a symbol similar this  "Z", and small grey boxes are appearing next to line ends, with red lines contained within them. These are not the only abnormalities Im facing, since when I try to use dim aligned, and I select the second point, it doesnt lock on and align the dimention like it should, instead the dimention just randomly inserts itself nearby and often and a funny angle. Finally, Im trying to get on with other stuff since this is fustrating, but when I paste objects they dont paste at the insertion point but elsewhere within the workspace. Also, when viewing in the layout or layout/model space, most of my linework looks displaced, broken or at tangents.

Please help guys, many thanks.