After light build, weird effects in objects. help please

After hard, crazy, interesting, tutorials in this forum, I gained a lot of knowledge. so thanks Everyone.

so problem is i finely build the light only. after that, shadows and some mashe edges have a weird effect.
(sorry for bad English im from sri lanka)

may i increase the light map resolution? but problem is when i increase the light map editor crashing while build. so any workaround?

my current light resolution

help please