An MSExchangeIS 9518 event that has error code 0xfffffc01 occurs when you try to mount a mailbox or a public folder store

When you try to mount a mailbox store or a public folder store in Microsoft Exchange 2000 Server or in Microsoft Exchange Server 2003, you experience the following symptoms:

• You receive the following error message:
  An internal processing error has occurred. Try restarting the Exchange System Manager or the Microsoft Exchange Information Store service, or both.
  
  ID no: c1041724
  Exchange System Manager
• An event that resembles the following event is logged in the Application log:

  Event Type: Error
  Event Source: MSExchangeIS
  Event Category: General
  Event ID: 9518
  Date: date
  Time: time
  User: N/A
  Computer: SERVERNAME
  Description: Error 0xfffffc01 starting Storage Group /DC=COM/DC=EXAMPLE/CN=CONFIGURATION/CN=SERVICES/CN=MICROSOFT EXCHANGE/CN=FIRST ORGANIZATION/CN=ADMINISTRATIVE GROUPS/CN=FIRST ADMINISTRATIVE GROUP/CN=SERVERS/CN=ServerName/CN=INFORMATIONSTORE/CN=FIRST STORAGE GROUP on the Microsoft Exchange Information Store. Storage Group - Initialization of Jet failed.

This problem occurs if an incorrect drive letter is set for the Exchange database files or for the log files. Error code 0xfffffc01 indicates that a drive letter has changed for the Exchange database files or for the log files.

Alternatively, this problem may occur if antivirus software is blocking write access to the drives that contain the Exchange database or the transaction log files. To determine if your Antivirus software is causing this problem, temporarily disable the antivirus software in the Services console. Then, try to mount the affected databases. If the databases mount successfully, contact the antivirus vendor for the latest build of the software.

To resolve this problem if an incorrect drive letter is set for the Exchange database files or for the log files, verify the database path and the log file path by using Exchange System Manager. To do this, follow these steps:

1. Start Exchange System Manager. To do this, click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. If administrative groups are displayed in Exchange System Manager, expand Administrative Groups, and then expand the administrative group in which you experience the problem.
3. Expand Servers, and then expand the server on which you experience the problem.
4. Right-click the storage group that contains the store that you cannot mount, and then click Properties.
5. On the General tab, examine the path that appears in the Transaction log location box. Then, examine the path that appears in the System path location box.
   
   If these paths are incorrect, click Browse to locate the folder that contains the transaction log files or the database files. By default, the transaction log files and the database files are located in the following folder:
   %PROGRAMFILES%\Exchsrvr\mdbdata
6. Click OK.
7. Follow steps 3 through 5 for each storage group that may be present to verify the database path and the transaction log file path.
8. After you verify the database path and the transaction log file path for each storage group, verify the database paths for each store in each storage group. To do this, follow these steps:
   1. Expand a storage group. For example, expand First Storage Group.
   2. Right-click StoreName (ServerName), and then click Properties.
   3. Click the Database tab, and then verify the path that appears in the Exchange database box. Then, verify the path that appears in the Exchange streaming database box.
   4. If a particular path is incorrect, click Browse to locate the correct folder for the database file. By default, the Exchange database file (.edb) and the Exchange streaming database file (.stm) are located in the following folder:
      %PROGRAMFILES%\Exchsrvr\mdbdata
   5. Click OK.
   6. Follow steps 8b through 8e to verify the paths for each mailbox store or public folder store that is present in each storage group.
9. Mount the mailbox store or the public folder store.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base: