It's probably some sort of inherited setting, that didn't get upgraded.
I use Xubuntu, which doesn't really use Compiz -- there are some simple compositing effects available, built-in.
Do the reinstall, it's worth it and if you export Synaptic markings to your home-directory, back it up and then copy it back after the install (and import the markings to Synaptic) you are at least 90% back to normal (and the last 10% are pretty minor.)
I usually do an app-by-app restore of my home-directory, though, especially if there are some settings issues.
cap
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