I've not had this particular issue with OpenSCAD / Cinnamon, but I have had other window / icon issues with Cinnamon on Mint 13. To resolve the missing icons try restarting cinnamon by right clicking on your taskbar, select troubleshooting, and restart cinnamon. As for OpenSCAD freezing, I can only suggest following Daid's advice and getting the latest version.
Get the latest version from source. Because most likely the package is outdated. There where quite a few bugs in older OpenSCAD versions.
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