This user agent
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
is not recognized and shown as Netscape 4.0 and unknown OS.
For me it looks like MS IE 7 and Windows XP.
Trunk UserAgentParser appears to handle it properly (IE7 on Win XP).
Please test with libs/UserAgentParser/UserAgentParser.test.php and advise your results, php version, and php info/configuration (eg disabled functions).