What OS you on?
Linux
Also, at the moment it happens, does the missing blk file reside on disk?
It seems it does:
$ ls .bitcoin/blocks/blk01147.dat -lh
-rw------- 1 user user 96M ene 28 21:55 .bitcoin/blocks/blk01147.dat
Is restarting the DB fixing it?
Yup.
ArmoryDB aborts and when I start it again, it seems to run fine.