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It's a common issue. There is a fix from the UNO website...

While you wait, there is a easy workaround pointed out by Splunk23, that will allow you to use UNO:

"...Just navigate to /System/Library/CoreServices/ and open up "SystemVersion.plist" and change the "SystemVersion" string from 10.4.10 to 10.4.9 and save the file. Then open up UNO and install it like before. Now just change the .plist file back to the way it was..."
 
Yeah, it was a simple fix. Just temporarily modify a .plist file so that the system thinks it's 10.4.9 and then install Uno, then change back the .plist file.
 
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