The crash is a known issue just press ESC
There is no rotation in private games it's just how it is.
You could write a script for it or even better use a mapvote which would allow you to vote at the end without going back to the lobby. There are several on the forum but I can recommend mine for ease of use and since it's the most documented
https://forum.plutonium.pw/topic/26669/mp-modern-warfare-3-mapvote/
Another solution could be hosting a local dedicated server which supports rotation but it would be a fixed rotation playing in the same order so imo a mapvote in custom games is better
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