Exception message as reported by Nexus Mod Manager v0.18.9:
 
Tracing an Unhandled Exception:
Exception:
Message:

The execution has failed due to the bug in the SevenZipSharp.

Please report about it to http://sevenzipsharp.codeplex.com/WorkItem/List.aspx, post the release number and attach the archive.
Full Trace:

SevenZip.SevenZipException: The execution has failed due to the bug in the SevenZipSharp.

Please report about it to http://sevenzipsharp.codeplex.com/WorkItem/List.aspx, post the release number and attach the archive.
at SevenZip.SevenZipBase.ThrowException(CallbackBase handler, Exception[] e)
at SevenZip.SevenZipBase.CheckedExecute(Int32 hresult, String message, CallbackBase handler)
at SevenZip.SevenZipCompressor.CompressStreamDictionary(Dictionary2 streamDictionary, Stream archiveStream, String password)
at SevenZip.SevenZipCompressor.CompressStreamDictionary(Dictionary2 streamDictionary, String archiveName, String password)
at Nexus.Client.Util.Archive.ReplaceFile(String p_strFileName, Byte[] p_bteData)
at Nexus.Client.Mods.Formats.FOMod.FOMod.ReplaceFile(String p_strPath, Byte[] p_bteData)
at Nexus.Client.Mods.Formats.FOMod.FOMod.UpdateInfo(IModInfo p_mifInfo, Boolean p_booOverwriteAllValues)
at Nexus.Client.ModManagement.ModRegistry.RegisterMod(String p_strModPath, IModInfo p_mifTagInfo)
at Nexus.Client.ModManagement.AddModTask.RegisterModFiles(IList1 p_lstAddedMods)
at System.EventHandler1.Invoke(Object sender, TEventArgs e)
at Nexus.Client.ThreadedBackgroundTask.OnTaskEnded(TaskEndedEventArgs e)
at Nexus.Client.ThreadedBackgroundTask.RunThreadedWork(Object p_objArgs)
at Nexus.Client.ThreadedBackgroundTask.RunThread(Object p_objArgs)
at Nexus.Client.Util.Threading.TrackedThread.RunParameterizedThread(Object p_objParam)
at System.Threading.ExecutionContext.runTryCode(Object userData)
at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart(Object obj)
 
The SevenZipSharp C# library version used by the Nexus Mod Manager program is 0.64.3890.29348.
 
The zip file that caused this exception to happen can be found on the Nexus web site; I'm not sure if I should post it here as it is not mine. Well, I'll post it but if anyone has any issues with this then please just delete it here.
 
Download location of the failing archive:
http://skyrim.nexusmods.com/download/68493
(The author of the file is character named "Onestick" and the containing page is: http://skyrim.nexusmods.com/mods/18189 )
 
And FYI, the standalone 7-Zip file verify and extract of this archive does not give any errors and work just fine.