Missing Item(s) on level 27, Monster Condo:

In single-player games, a player will typically exit this
level with an Items score below 100%, even after picking up
or touching all accessible items.
This is due to the fact that two Computer Area Map items
exist on this level, but the player is only allowed to take
one of them.
(A Computer Area Map item is intangible to a player who
already possesses one.  A player who tries to pick up both
will pick up the first, but only walk through the second.)
On level 27, a remaining Computer Area Map item can account
for as much as 2% of all attainable Items on the level.