How many 3rd party aircraft do you have installed? Too many aircraft is the common cause of this problem. http://www.simviation.com/lair/cfs2faq.htm
In my experience, scenery should not cause error messages - providing you install it correctly & activate via the Scenery Library. http://www.simviation.com/lair/cfs2scenclinc.htm

To use imported airfields in the MB they will need adding to airbases.dat. http://www.simviation.com/lair/Scene2MbDb.html

Quote:

Not to my knowledge. There is a limit to the number of new areas you can add to Scenery.cfg but this should not cause errors. Any conflicts should be easy enough to fix - providing you installed all your 3rd party scenery separately & activated it via the Scenery Library. Simply go to the Scenery Library & deactivate the suspect area. When you identify a problem area, delete it from the Scenery Library before removing the files. If you pasted BGL files direct to the Scenery folder you could have a problem. The only answer might be a complete Uninstall/Install of CFS2.

Dick You're right that our memories are weak. Mine is getting worse by the day. LOL
Providing you installed all your 3rd party scenery separately & activated via the Scenery Library there should be no problems. The conflicting area can then be tracked down by de-activating areas systematically from the Scenery Library. The problem arises if you paste BGL files direct to the CFS2\Scenery folder or unzip downloaded scenery direct to the sim. This makes it difficult to remember file names or know exactly where to find them. It's also possible that the database is actually corrupt as shown by the error message.

The best way out in your case might be a duplicate install of CFS2. You obviously need enough free space on your HD.
To do this, simply rename the existing CFS2 root directory folder to any other name.
Then insert the CD & install in the usual way.
You will now have two separate versions of CFS2 which will run independently. Use the original install as a backup. You can transfer the files/folders you know are working properly. Things like gauges should be OK. When you're done it's safe to delete the complete directory folder for the original.

PS. You can have as many duplicate installs as you wish, providing there's enough space on your HD. Many people I know run several separate versions of CFS2, for example - CFS2 Europe, CFS2 Pacific & CFS2 Jets.

Thanks Hagar and Mathias for your valuable tips.
Hagar: if your memory goes down by the day, it must have been of  "inhuman" proportions a
couple of years ago, measured against this huge amount of sim things you still remember
today! I read about the duplicates in the forum and I just came to the conclusion to try a
duplicate install when I found your messages.
Since Mathias' clever idea is less effortful I tried it first, but unfortunately without success.
Let's track it down. I think the problem A&P and I experience has to do with the scenery.
A&P used only the stock aircraft and I have no more than 60 aircraft active.
Moreover, I followed Hagar's tut-advice and removed 5 aircraft, again without succes. I had
several 3rd party sceneries installed that worked fine. So the problem is not just installing 
imported sceneries, but maybe the way in which it was installed. I also remember (just lucky)
the things that I did not do. I didnot pasteBGL files directly to the CFS2\Scenery folder nor did I
unzip downloaded scenery directly to the sim. The problem of A&P may lie here, he says he
tested it by copy and pasting into the scenery folder.
I also remember (again just lucky I guess) I had erroneously installed and activated 2 mesh
sceneries with the same name ( "java-mesh") from different folders (ADDON/java-mesh andSCENERYDB/java-mesh) at 2 different layers (1 and 17). Here's a weak spot: I dont
remember whether I flew with this duplicate messh or immediately de-activated and deleted the
duplicate. The last thing I remember (really!) is that I had installed and activated 2 mesh
sceneries in a single Scenery Library session. Hagar: what do you mean with "you installed all
your 3rd party scenery separately"? In separate Scenery Library sessions or in separate folders?
If the second is correct, my mistake of having same-name/different folder sceneries installed
could be the problem. Anyway: does this ring a bell?
The idea of independent CFS2 versions is intriguing, I didnot know CFS2 has that far developed... I will duplicate independently of this misty data base problem and do some tests
on it. How do you select the CFS2 version you wanna play with? By interchanging the root-folder
names?
Nice ideas guys, thanks alot!

Hi Hagar and others interested. Our memories are weak, but mine..... Well, I found out why I got the data base corruption error. It had nothing to do with number of aircraft or faulty scenery installation. It resulted from 3rd party ship dp files with which I replaced the original ship dp's.
As Hagar advised I made a fresh duplicate CFS2 install. Next, I installed the 3rd party mesh and other scenery in the fresh CFS2 install and tested it. Everything worked perfect. Then I imported my 3rd party effects and aircraft in the fresh install. Again, everything worked perfect. Finally, I imported into the fresh install the complete ships folder from my old install, and WHAM, the data base corruption error was there. After replacing these faulty ships with the original ones, the error disappeared and in the fresh install everything worked perfect again. Also, after replacing the ships in the old install with the stock ships, the old install also worked perfect again! I only then remembered that I had been replacing ship dp files in the same session in which I installed 3rd party scenery. Memories..... The lesson of this might be: "Thou shall test, not just remember", or better: "Thou shall test and only then remember".
I then wondered what was wrong in the ships folder: some 3rd party ships I imported, or the 3rd party dp files that I had used to replace the original ones with. So I imported the 3rd party ships with their own dp files in the fresh install. Everything worked fine. Then I replaced the dp files of these ships with the ones I downloaded from a third party, and there it was again: the data base corruption error. After overwriting the new ship dp files with the original ones, everything was fine again.
Ever heard of this before? The 3rd party source of the dp files that cause the error  seems reliable to me, so I wonder whether this is a problem specific to Win-XP, like the aircraft MDL problem.
Well, I hope this may help others with the same problem.
See you later.

Hagar, you wrote:
"I suspect having the same area (java-mesh) activated twice from 2 different locations might cause some sort of conflict. This would not usually be possible as the Scenery Library will not accept it." I found itt really did accept the install and activation, but as said before, I dont remember whether I flew with it or deleted the entry after recognizing my error.

Hagar: I know that one has to delete CDP's after changing the DP's, and I usually do, but, you know, sometimes one forgets ....
So I deleted all CDP's I could find of the ships in the ships-folder causing the error, next renamed the SHIPS folder (to SHIPS-Correct) and renamed the SHIPS-Corrupt folder to SHIPS, and then ran CFS2 free flight. Unfortunately without succes, the error still occurred.
The CFG files in the SHIPS folder were never changed, so it all points to the DP's, dont you think?

Hagar: I was wrong about the CFG files. First, I imported the ships developed by the PHP Team. I then replaced the CFGs and DPs of the ships with the ones by Blade-etal (CFS2Bladeeffectcollv2). I tested this with the fresh install: no problems. Next, I replaced only the DPs with those from AF_ShipDPPackage-1. After this, the data base corruption occurs. My guess: the AF DPs may require the stock CFGs, so a conflict arises because the stock CFGs were changed.