There are three main causes of corruption in Access/Jet mdb files.

Database is Suspect/Corrupted Due to Interrupted Write Operation

You should always quit Access properly by clicking Exit or Close on the File menu. If a database is open and writing data when Access is abnormally shut down, the Jet database engine may mark the file as suspect/corrupted. This can happen if the computer is manually turned off without first shutting down Windows or if power is lost. Other situations may not shut down Access but may still interfere with Jet's writing of data to the disk while the database is open. This can happen, for instance when networks experience data collisions or disk drives malfunction. If any of these interruptions occur, then Jet may mark the database as potentially corrupted.

When Jet begins a write operation, it sets a flag, and resets the flag when the operation is completed. If a write operation is interrupted, the flag remains set. When you try to open that database again, Jet determines that the flag is set and reports that the database is corrupted. In most cases, the data in the database is not actually corrupted, but the set flag alerts Jet that corruption may have occurred. In cases such as this, compacting and/or repairing the database can typically restore the database.

Faulty Networking Hardware

In this case, the file corruption does not involve the Jet database engine; rather the file is literally corrupted by some outside cause. The cause can be one or more links in the hardware chain between the computer that the database resides on and the computer that has the database open. This list includes, but is not limited to, network interface cards, network cabling, routers, and hubs.

Hardware-based corruption is typically indicated by .mdb files that cannot be restored through the use of compacting, repairing, or Jetcomp. Hardware corruption will typically recur until the responsible hardware is repaired or replaced.

In addtion to networking hardware the following can also cause corruption:

• Faulty network interface cards
• Faulty, slow or improperly configured network software
• If you are running on Windows 95 or Windows 98, crashes in unrelated programs, drivers and utility software (such as screensavers) can be responsible.

Opening and Saving the Data File in Another Program

There is no way to recover a data file that was opened and then saved in a program other than Access. For example, Microsoft Word allows you to open an Access database and then save it (although it serves no good purpose to do so because if you open an MDB file in another program, all you can see are extended characters). Saving the file in this manner will cause the .mdb file to prompt you for a database password when you try to open it in Access even though the file may have never been password-protected in Access. The password prompt occurs in such cases because the first byte range that Access checks when it opens a file is where the database password would be. If that byte contains corrupted data, Access treats the file as being password protected. Even if there were a way to get around the password prompt in this case, the database would still be unrecoverable because the binary structure is scrambled and therefore unreadable to Access. Recovering a backup copy of the file is the only solution in this case.

Checking for data file corruption

If your product is not at least one of the versions listed below we do not recommend using the following procedure as you may lose data during the compact/repair function.

• Summit Event Manager - Pro 2000 Edition - Version 7.07 or higher
• Summit Event Manager - Pro Edition - Version 9.01 or higher
• Summit Event Manager - Light Edition - Version 8.01 or higher
• Summit Contact Manager - Version 3.03 or higher

To check if a data file is corrupt, compact and Repair it from the File Menu. The above products have an enhanced compact/repair function that checks the integrity of a compacted file before offering deletion of the original source file. This enhancement is to prevent loss of data through table truncation if you attempt to compact/repair a badly corrupted data file.

The enhanced compact/repair function is not available in older software products.

For more information on repairing corrupt data files, the causes of corruption and ways of troubleshooting and eliminating the causes of corruption click on one of the following Microsoft links:

For Access Version 2 - http://support.microsoft.com/support/kb/articles/Q109/9/53.ASP

For Access 97 - http://support.microsoft.com/support/kb/articles/Q279/3/34.ASP

For Access 2000 - http://support.microsoft.com/support/kb/articles/Q209/1/37.ASP

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