I'm getting the same thing on Xubuntu 7.04 Feisty Fawn, ATI Mobility Radeon X600 with proprietary drivers:
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2007-06-18T14:50:44Z INFO: idle_startup: Initializing Window
2007-06-18T14:50:44Z INFO: login_show: Initializing Login Screen
2007-06-18T14:50:44Z INFO: login_show: Decoding Images
2007-06-18T14:50:44Z INFO: login_show: Setting Servers
2007-06-18T14:50:45Z INFO: LLSDXMLParser::Impl:

arse: XML_STATUS_ERROR parsing:if (hour < 5)
2007-06-18T14:50:51Z INFO: idle_startup: Attempting login as: YonNii Kamachi
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: Current Directories:
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: CurPath: /opt/secondlife
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: AppName: SecondLife
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: ExecutableFilename: do-not-directly-run-secondlife-bin
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: ExecutableDir: /opt/secondlife/bin
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: ExecutablePathAndName: /opt/secondlife/bin/do-not-directly-run-secondlife-bin
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: WorkingDir: /opt/secondlife/bin
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: AppRODataDir: /opt/secondlife
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: OSUserDir: /home/helge
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: OSUserAppDir: /home/helge/.secondlife
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: LindenUserDir: /home/helge/.secondlife/yonnii_kamachi
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: TempDir: /tmp
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: CAFile: /opt/secondlife/app_settings/CA.pem
2007-06-18T14:50:51Z INFO: dumpCurrentDirectories: SkinDir:
2007-06-18T14:50:51Z WARNING: parseFile: Couldn't open file /home/helge/.secondlife/yonnii_kamachi/overrides.xml
2007-06-18T14:50:51Z WARNING: parseFile: LLXmlTree parse failed. Line 1: Couldn't open file /home/helge/.secondlife/yonnii_kamachi/overrides.xml
2007-06-18T14:50:51Z WARNING: loadFromFile: Unable to open control file /home/helge/.secondlife/yonnii_kamachi/overrides.xml
2007-06-18T14:50:51Z WARNING: parseFile: Couldn't open file /home/helge/.secondlife/yonnii_kamachi/settings.xml
2007-06-18T14:50:51Z WARNING: parseFile: LLXmlTree parse failed. Line 1: Couldn't open file /home/helge/.secondlife/yonnii_kamachi/settings.xml
2007-06-18T14:50:51Z WARNING: loadFromFile: Unable to open control file /home/helge/.secondlife/yonnii_kamachi/settings.xml
2007-06-18T14:50:51Z INFO: init_start_screen: Loading startup bitmap...
2007-06-18T14:50:51Z WARNING: setLastError: Unable to open file for reading FILE:/home/helge/.secondlife/yonnii_kamachi/screen_last.bmp
2007-06-18T14:50:51Z INFO: init_start_screen: Bitmap load failed
2007-06-18T14:50:51Z INFO: idle_startup: Resolving Agni userserver domain name userserver.agni.lindenlab.com
2007-06-18T14:50:52Z INFO: on_userserver_name_resolved: ...Userserver resolved to 66.150.244.151:12036
2007-06-18T14:50:52Z INFO: idle_startup: Verifying message template...
2007-06-18T14:50:56Z INFO: idle_startup: Message template is current!
2007-06-18T14:50:56Z INFO: LLMessageSystem::disableCircuit for 66.150.244.151:12036
2007-06-18T14:50:56Z INFO: LLCircuit::removeCircuitData for 66.150.244.151:12036
2007-06-18T14:50:56Z WARNING: checkMessages: Packet from invalid circuit 66.150.244.151:12036
2007-06-18T14:50:56Z INFO: authenticate: Authenticating: YonNii Kamachi,
2007-06-18T14:50:56Z INFO: authenticate: Options: inventory-root, inventory-skeleton, inventory-lib-root, inventory-lib-owner, inventory-skel-lib, initial-outfit, gestures, event_categories, event_notifications, classified_categories, buddy-list, ui-config, login-flags, global-textures, END
2007-06-18T14:50:56Z INFO: LLUserAuth::authenticate: uri=https://login.agni.lindenlab.com/cgi-bin/login.cgi
2007-06-18T14:50:56Z WARNING: checkMessages: Packet from invalid circuit 66.150.244.151:12036
2007-06-18T14:50:56Z WARNING: checkMessages: Packet from invalid circuit 66.150.244.151:12036
2007-06-18T14:50:56Z WARNING: checkMessages: Packet from invalid circuit 66.150.244.151:12036
2007-06-18T14:50:59Z INFO: transferRate: Buffer size: 48917 B
2007-06-18T14:50:59Z INFO: transferRate: Transfer size: 5069 B
2007-06-18T14:50:59Z INFO: transferRate: Transfer time: 2.91611 s
2007-06-18T14:50:59Z INFO: transferRate: Transfer rate: 13.904 Kb/s
2007-06-18T14:50:59Z INFO: authResponse: Processed response: 0
2007-06-18T14:50:59Z INFO: LLCircuit::addCircuitData for 64.129.41.74:13006
2007-06-18T14:50:59Z INFO: saveToFile: Saving settings to file: /home/helge/.secondlife/user_settings/settings.xml
2007-06-18T14:50:59Z WARNING: parseXml: Bone without position
2007-06-18T14:50:59Z WARNING: parseXml: Error parsing bone in skeleton file
2007-06-18T14:50:59Z i686-linux-client-releasefordownload/newview/llvoavatar.cpp(1521) : error
2007-06-18T14:50:59Z ERROR: initClass: Error parsing skeleton XML file: /opt/secondlife/character/avatar_skeleton.xml
LogLock::LogLock: failed to get mutex for log
LogLock::LogLock: failed to get mutex for log
LogLock::LogLock: failed to get mutex for log
LogLock::LogLock: failed to get mutex for log
LogLock::LogLock: failed to get mutex for log