Seems like your search index got corrupted somehow, to fix it open a terminal and run these commands:
zeitgeist-daemon --quit cd ~/.local/share/zeitgeist/ rm -rvf fts.index/ zeitgeist-daemon &
Afterwards your database will be reindexed, wait a while for this to happen (there'll be lots of output in the terminal) and then try again.
Seems like your search index got corrupted somehow, to fix it open a terminal and run these commands:
zeitgeist-daemon --quit share/zeitgeist /
cd ~/.local/
rm -rvf fts.index/
zeitgeist-daemon &
Afterwards your database will be reindexed, wait a while for this to happen (there'll be lots of output in the terminal) and then try again.