If you are using OpenJDK you need to run this problem disabling Java official JRE compatibility.
"java -Dsmartsvn.checkIncompatibleJava=false -jar smartsvn.jar"
Link: http://www.syntevo.com/smartsvn/download.html
CHANGELOG
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SmartSVN 6.6.11 (2011-12-20)
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Fixed Bugs
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- https-protocol: possible SSL connection problems (regression)
- Refresh: possible slowness related to SVN 1.7 check
- Revision Graph: internal error for Show Merge Source for large graphs