见：
http://support.microsoft.com/kb/317909/zh-cn，时间关系，自己先看看吧
摘抄如下：
"Invalid Access Code" error message when you use Visual SourceSafe automation
SYMPTOMS
When you use an add-in for Microsoft Visual SourceSafe that you created with Microsoft Visual Studio .NET, you receive the following error message when methods are called:
Microsoft Visual SourceSafe
Invalid access code (bad parameter)
CAUSE
This problem occurs because Microsoft .NET runtime uses the QueryInterface method to look for an interface in Visual SourceSafe that Visual SourceSafe does not support.
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RESOLUTION
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.
To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=support (
http://support.microsoft.com/contactus/?ws=support)
