To reproduce this bug (logged in, in Firefox or Chrome):
- Go to any item
- click add property
- type "language" (with all the letters)
- from the drop-down list select "language - language of a work"
- the value field loads endlessly
Note: this doesn't happen with other properties, and it doesn't happen with that one either if you type "lan" only. Maybe there is a conflict between "language" and "official language"?