After a "Fatal Error" message I uninstalled then reinstalled FSX. Then installed SP1 and SP2. After each installation I restarted the computer before doing the next installation.I deleted all previous FSX files before the installation.I then launched FSX succesfully.Next I installed the PMDG 747-800 but ran into a problem with a message saying that certain DLL's could not be found.Hoping that a "Repair" of FSx may solve the problem I resinserted the CD's and activated a repair.However after launching for a second time that "Fatal Error" message appeared again.Any comments would be helpful.Cliff Harris

Have you checked your event logs for the root of the problem?If you're running W7/vista, go to the start menu, and search for event viewer, open it, go to Windows Logs on the left, then Application, then look down the list for errors. If you click on one it'll give details of the specific file that caused the error. If you're running XP, it's a similar process: http://support.microsoft.com/kb/308427I've had fatal errors in the past from uiautomationcore.dll. This fixed it:http://forums1.avsim.net/index.php?showtopic=267596

After a "Fatal Error" message I uninstalled then reinstalled FSX. Then installed SP1 and SP2. After each installation I restarted the computer before doing the next installation.I deleted all previous FSX files before the installation.I then launched FSX succesfully.Next I installed the PMDG 747-800 but ran into a problem with a message saying that certain DLL's could not be found.Hoping that a "Repair" of FSx may solve the problem I resinserted the CD's and activated a repair.However after launching for a second time that "Fatal Error" message appeared again.Any comments would be helpful.Cliff Harris

I agree with Nick but you already know the offending .dll. Your best bet is to google the offending .dll that could not be found and/or the error message displayed after the CTD. I'm certain you will find the solution there. BTW, there are several types of CTD's/Fatal Error messages in FSX. In the future you need to be more specific about the fatal error message and those details can be found in the Event Viewer.Best regards,Jim

After a "Fatal Error" message I uninstalled then reinstalled FSX. Then installed SP1 and SP2. After each installation I restarted the computer before doing the next installation.

That was your first mistake. Reinstalling FS (any version) should always be the absolute LAST desperate step, as 99% of the time the "error" is fairly easy to find and fix.In fact, most "errors" may be solved easily by renaming the fs9.cfg or fsx.cfg file and allowing the sim to build a fresh copy...

After a "Fatal Error" message I uninstalled then reinstalled FSX. Then installed SP1 and SP2. After each installation I restarted the computer before doing the next installation.I deleted all previous FSX files before the installation.I then launched FSX succesfully.Next I installed the PMDG 747-800 but ran into a problem with a message saying that certain DLL's could not be found.Hoping that a "Repair" of FSx may solve the problem I resinserted the CD's and activated a repair.However after launching for a second time that "Fatal Error" message appeared again.Any comments would be helpful.Cliff Harris

Cliff - after you did the "repair" - did you reinstall SP1 & SP2? You have to do this, and your note doesn't mention it.

Cliff - after you did the "repair" - did you reinstall SP1 & SP2? You have to do this, and your note doesn't mention it.

Yes, I did.But I think/hope I've nailed it with a final uninstall/install.But I've learned a lot from the helpfulness of you all and I appreciate it.Cliff

Good stuff. It's a bummer when you are faced with a decision like this, isn't it? :( :( :( .. and when you're finished and it works better than ever you'll know how great it feels! B)