The message "Windows has blocked access to these files to help protect your computer" continually appears when trying to use Windows Explorer to extract a .ZIP file on Windows XP SP2.

On Windows Server 2003 SP1 the extract dialogue does nothing when clicking Next on the "Select a Destination" dialogue.

Using Attachment Manager Group Policy to add the .ZIP extension to the inclusion list for low risk file types does not resolve the issue.

The SEE_MASK_NOZONECHECKS environment variable does not resolve the issue.

The .ZIP file may have slashes embedded in the filenames.

Use a third party product to extract the file e.g. unzip command line in linux:

Archive:  File.zip
warning:  File.zip appears to use backslashes as path separators
warning:  stripped absolute path spec from /Content.zip
  inflating: Content.zip

Other Possible Solutions

For Individual Files: Unblock the file
- Right-click the blocked file, and then click Properties.
- In the General tab, click Unblock.

For all files: Set the SEE_MASK_NOZONECHECKS environment variable
- Right click on My Computer and select properties from the context menu
- Select the Advnaced tab
- Click on the Environment Variables button
- In System Variable click New
- Enter SEE_MASK_NOZONECHECKS for Variable Name
- Enter 1 for Variable Value
- Click OK
- Click OK
- Restart the computer

By file type: Configure File Types as Low Risk in Attachment Manager
GPO:
- Location: User Configuration\Administrative Templates\Windows Components\Attachment Manager
- Policy: Inclusion list for low file types
Registry:
- Key: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
- Value: LowRiskFileTypes
- e.g. "LowRiskFileTypes"=".exe;.cmd"

By file server: Set Zonemap for Server to Local Intranet
- Key: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\<server name>
- e.g. HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\server01
- Value: "file"=dword:00000001

For UNC Files: Set UNCAsIntranet
- Key: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
- Value: "UNCAsIntranet"=dword:00000001

Description of how the Attachment Manager works in Windows XP Service Pack 2
http://support.microsoft.com/kb/883260

The Open File - Security Warning dialog box is displayed when you try to silently install a hotfix or an update by using a Visual Basic script in Windows XP Service Pack 2
http://support.microsoft.com/kb/889815

Internet Explorer security zones registry entries for advanced users
http://support.microsoft.com/kb/182569