I recently ran across this issue in one of my data conversions for a client. Same error but different symptoms. I was able to narrow the issue down to a specific concatenation of dateparts and then converting to a datetime as well as a specific join causing the problem on one of my queries.

My issue was resolved by adding indexes on the join table.

example:

select convert(datetime, A.MO + '/' + A.DY + '/' A.YR)

from A

join B on A.id = b.id

left join C on A.id = C.id

AND a.id2 = C.id2

In the example above there weren't indexes on table C. As soon as I added them on id and id2 the error went away. Hope this inspires you to look a different direction and resolve your issue.