Installation of Service Pack 4 for Exchange Server 5.5 stops with "Files in Use" error

When you try to install Service Pack 4 for Microsoft Exchange Server 5.5, you may receive an error message that states that the following files are in use:

• Mdbperf.dll
• Msesperf.dll
• Mtaperf.dll
• Perfdsa.dll

Therefore, installation of the service pack cannot continue.

Performance Monitor uses these files to track MSExchangeMTA Connections. However, Performance Monitor does not currently run either on this computer or remotely. If you try to run Performance Monitor locally, it does not start.

If you turn off services and restart the server, the issue is not resolved.

To resolve this issue, you must rename these files, and then reinstall the service pack. To do this, follow these steps:

1. Open Windows Explorer.
2. Locate the drive:\Exchsrvr\BIN folder.
3. Right-click the Mdbperf.dll file, and then click Rename.
4. Type Mdbperf.dll.old, and then press ENTER.
5. Repeat steps 3 through 4 for each file in the preceding list. Rename each file with an .old file name extension.
6. Close Windows Explorer.
7. Install Exchange Server 5.5 Service Pack 4.