为不同域中的用户授予对 SharePoint 的访问权限

我刚刚在虚拟服务器上完成了 SharePoint 网站的开发，目前正在将来自不同域的用户授予该网站。我是开发人员，而不是网络管理员。虚拟服务器不是域控制器，也没有安装 Active Directory。SharePoint 域是 SHAREPOINT，而我要授予访问权限的用户所在的域是 COMPANY。它们通过 LAN 连接。我已经为他们提供了指向该站点的链接，并通过 SharePoint 和 SQL Server 将他们添加为用户，这是我认为我需要做的所有事情。但是，当他们转到该链接时，该网站会向他们显示一个 SharePoint 错误页面，告诉他们访问被拒绝。问题归结为 SharePoint 的自定义 Web 部件。如果我从索引页面中删除该 Web 部件，他们就可以正常访问它。

在安全事件日志中，我显示以下内容：

Event Type: Failure Audit
Event Source:   Security
Event Category: Object Access 
Event ID:   560
Date:       3/18/2010
Time:       11:11:49 AM
User:       COMPANY\ThisUser
Computer:   SHAREPOINT
Description:
Object Open:
    Object Server:  Security Account Manager
    Object Type:    SAM_ALIAS
    Object Name:    DOMAINS\Account\Aliases\00000404
    Handle ID:  -
    Operation ID:   {0,1719489}
    Process ID: 416
    Image File Name:    C:\WINDOWS\system32\lsass.exe
    Primary User Name:  SHAREPOINT$
    Primary Domain: COMPANY
    Primary Logon ID:   (0x0,0x3E7)
    Client User Name:   ThisUser
    Client Domain:  PRINTRON
    Client Logon ID:    (0x0,0x1A3BC2)
    Accesses:   AddMember 
            RemoveMember 
            ListMembers 
            ReadInformation 

    Privileges: -
    Restricted Sid Count:   0
    Access Mask:    0xF

然后，连续四个：

Event Type: Failure Audit
Event Source:   Security
Event Category: Object Access 
Event ID:   560
Date:       3/18/2010
Time:       11:12:08 AM
User:       NT AUTHORITY\NETWORK SERVICE
Computer:   SHAREPOINT
Description:
Object Open:
    Object Server:  SC Manager
    Object Type:    SERVICE OBJECT
    Object Name:    WinHttpAutoProxySvc
    Handle ID:  -
    Operation ID:   {0,1727132}
    Process ID: 404
    Image File Name:    C:\WINDOWS\system32\services.exe
    Primary User Name:  SHAREPOINT$
    Primary Domain: COMPANY
    Primary Logon ID:   (0x0,0x3E7)
    Client User Name:   NETWORK SERVICE
    Client Domain:  NT AUTHORITY
    Client Logon ID:    (0x0,0x3E4)
    Accesses:   Query status of service 
            Start the service 
            Query information from service 

    Privileges: -
    Restricted Sid Count:   0
    Access Mask:    0x94

任何想法我需要授予用户哪些权限才能让他们访问 SharePoint？

我确实有一个来自其他域的用户能够正常查看该页面。对于该用户，我授予他以下权限：有什么方法可以将该用户与其他用户进行比较，并查看可能需要添加哪些权限？