Does this mean my WAD is corrupt?

[SayWhatOneMoreTime]

I can't walk past the black floor/ceiling and the rest of the map Is like this too, it just blocks me like it has a block everything action or whatever it is.

[bemused]

looks like an unclosed sector to me, but posting the wad itself may prompt some more experienced mappers to check it and see whats really happening instead of guessing from a screenshot :)