If the object has no UV seams marked (Mark Seam) to split the UV map the resulting smushed unwrap
can cause a crash as Blender tries to determine how it should be drawn (had that happen a few times). Try adding a seams around the back and base of the mesh to split the UV at those points, relaxing the UV should relieve that stress.
Alternatively, start a completely clean scene and
Append the mesh, try unwrapping again. If you get a crash then there's definitely something causing issues between the mesh and using
Unwrap.
Might also be worth checking to see if there are any
manifold elements (basically a non-contiguous surface or one where surface flow is interrupted in some way, typically by vertices, edges or face inside a mesh) - in
Edit Mode click
Select » Select All by Trait » Non Manifold, these can cause issues with the mesh's data such that Blender can crash during certain operations. For
Blender 2.8+ see how to fix non manifold issues here.