Use
http://fileforums.com/showthread.php?t=99317
Compress folder with files that get good ratio with pzlib
All other folders left merge into one and compress manually with freearc and add in records.ini.
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Or try to move out exe dll files and try again. then compress remaining files manually with freearc and add in records.ini.
This is a bug in freearc or ultraarc in some cases.