ruario at my Opera community (an Opera employee) has made research and he determined that at least for Opera deb file, the issue is with lzma not being present in default Ubuntu install. Here's the full discussion and ruario's research's conclusion:
http://my.opera.com/community/forums/topic.dml?id=1124872&t=1318873023&page=1#comment10564932
ruario at my Opera community (an Opera employee) has made research and he determined that at least for Opera deb file, the issue is with lzma not being present in default Ubuntu install.
Here's the full discussion and ruario's research's conclusion:
http:// my.opera. com/community/ forums/ topic.dml? id=1124872& t=1318873023& page=1# comment10564932