Il modo migliore è provare a usare il menu contestuale Open With...
per impostare Explorer come gestore di file predefinito.
Comunque, se questo non funziona puoi provare quanto segue per forzare Explorer a gestire il file ZIP. (http://www.vistaheads.com/forums/microsoft-public-windows-vista-general/270951-vista-how-do-you-restore-default-behaviour-zip-other-file-types.html)
Crea un file .reg con quanto segue:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\.zip]
"PerceivedType"="compressed"
"Content Type"="application/x-zip-compressed"
@="CompressedFolder"
[HKEY_CLASSES_ROOT\.zip\CompressedFolder]
[-HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.zip\UserChoice]
[HKEY_CLASSES_ROOT\.zip\CompressedFolder\ShellNew]
"Data"=hex:50,4b,05,06,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"ItemName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,\
6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,\
00,7a,00,69,00,70,00,66,00,6c,00,64,00,72,00,2e,00,64,00,6c,00,6c,00,2c,00,\
2d,00,31,00,30,00,31,00,39,00,34,00,00,00
[HKEY_CLASSES_ROOT\.zip\OpenWithProgids]
"CompressedFolder"=""
[HKEY_CLASSES_ROOT\.zip\PersistentHandler]
@="{098f2470-bae0-11cd-b579-08002b30bfeb}"
[HKEY_CLASSES_ROOT\CompressedFolder]
@="Compressed (zipped) Folder"
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
00,6f,00,6f,00,74,00,25,00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
32,00,5c,00,7a,00,69,00,70,00,66,00,6c,00,64,00,72,00,2e,00,64,00,6c,00,6c,\
00,2c,00,2d,00,31,00,30,00,31,00,39,00,35,00,00,00
[HKEY_CLASSES_ROOT\CompressedFolder\CLSID]
@="{E88DCCE0-B7B3-11d1-A9F0-00AA0060FA31}"
[HKEY_CLASSES_ROOT\CompressedFolder\DefaultIcon]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,7a,00,69,00,\
70,00,66,00,6c,00,64,00,72,00,2e,00,64,00,6c,00,6c,00,00,00
[HKEY_CLASSES_ROOT\CompressedFolder\shell]
@="none"
[HKEY_CLASSES_ROOT\CompressedFolder\shell\find]
"SuppressionPolicy"=dword:00000080
[HKEY_CLASSES_ROOT\CompressedFolder\shell\find\command]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
00,5c,00,45,00,78,00,70,00,6c,00,6f,00,72,00,65,00,72,00,2e,00,65,00,78,00,\
65,00,00,00
[HKEY_CLASSES_ROOT\CompressedFolder\shell\find\ddeexec]
@="[FindFolder(\"%l\", %I)]"
[HKEY_CLASSES_ROOT\CompressedFolder\shell\find\ddeexec\application]
@="Folders"
[HKEY_CLASSES_ROOT\CompressedFolder\shell\find\ddeexec\topic]
@="AppProperties"
[HKEY_CLASSES_ROOT\CompressedFolder\shell\Open]
[HKEY_CLASSES_ROOT\CompressedFolder\shell\Open\Command]
@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,\
00,5c,00,45,00,78,00,70,00,6c,00,6f,00,72,00,65,00,72,00,2e,00,65,00,78,00,\
65,00,20,00,2f,00,69,00,64,00,6c,00,69,00,73,00,74,00,2c,00,25,00,49,00,2c,\
00,25,00,4c,00,00,00
"DelegateExecute"="{11dbb47c-a525-400b-9e80-a54615a090c0}"
[HKEY_CLASSES_ROOT\CompressedFolder\ShellEx]
[HKEY_CLASSES_ROOT\CompressedFolder\ShellEx\ContextMenuHandlers]
[HKEY_CLASSES_ROOT\CompressedFolder\ShellEx\ContextMenuHandlers\{b8cdcb65-b1bf-4b42-9428-1dfdb7ee92af}]
@="Compressed (zipped) Folder Menu"
[HKEY_CLASSES_ROOT\CompressedFolder\ShellEx\DropHandler]
@="{ed9d80b9-d157-457b-9192-0e7280313bf0}"
[HKEY_CLASSES_ROOT\CompressedFolder\ShellEx\StorageHandler]
@="{E88DCCE0-B7B3-11d1-A9F0-00AA0060FA31}"
Poi, in un prompt dei comandi admin digitate:
regsvr32 zipfldr.dll
Un altro suggerimento che ho visto è di andare semplicemente nell'editor dei programmi predefiniti nel Pannello di controllo e rimuovere l'associazione che hai attualmente. Tuttavia, questo era per XP e non sono sicuro che funzionerà per Vista. Tuttavia, potresti provare questo prima di giocare con il registro di sistema.