Access数据库出现的0x80004005 Unspecified error问题及解决方案：
问题的分析和解决：

我反复的查找原因，不得其解，在MSDN里找到了三篇相关的文章：其中这一篇还有点道理，与我的错误原因达的上边。
ms-help://MS.MSDNQTR.2005APR.1033/enu_kboledb/oledb/251254.htm
SYMPTOMS
When trying to connect to an Access .mdb file, an ODBC error is returned stating "Disk or Network Error". The Microsoft OLE DB Provider for the Microsoft Jet database engine may also return an "Unspecified error" (error code = 0x80004005) message.

The problem can occur only when the data source is opened under the Microsoft Internet Information Server (IIS) or a Microsoft Windows NT service but not under a logged-on user account.
CAUSE
Jet creates a temporary file when the engine is started. In doing so, it first checks the TMP environment variable and uses that path to define where the temporary file is created. If it doesn't see a TMP environment variable, it looks for the TEMP environment variable. If TEMP is not defined, it then uses the Windows folder (\WINDOWS or \WINNT).