1. Create terrain
2. In inspector, choose paint details.
3. choose "Edit Details"
4. Add detail mesh. Any simple mesh is sufficient.
5. Confirm by clicking "Add"

Unity Crashes.

ErrorLog snippet:
Unity.exe caused an Access Violation (0xc0000005)
in module Unity.exe at 0023:009d3603.

Error occurred at 2013-09-09_142108.
C:\Program Files (x86)\Unity\Editor\Unity.exe, run by Erland.
26% memory in use.
0 MB physical memory [0 MB free].
0 MB paging file [0 MB free].
0 MB user address space [3200 MB free].
Read from location 00000048 caused an access violation.