Extremely worried - FS2004 won't start!!

First uninstall the last add-on from the Sim.

One of two ways it might get started.
Delete your FS9.cfg and let the Sim rebuild a new one.
Delete the log file and let the Sim rebuild a new one.

Unfortunately things have got progressively worse.

I turned the PC off for a few minutes and then went to restart it. However it now won't even boot up, giving me a completely blank screen.

No message, nothing shows on the screen at any time.

I took this from another site.

If Windows XP is the only operating system installed on your computer, booting into Safe Mode with these instructions.

If the computer is running, shut down Windows, and then turn off the power
Wait 30 seconds, and then turn the computer on.
Start tapping the F8 key. The Windows Advanced Options Menu appears. If you begin tapping the F8 key too soon, some computers display a "keyboard error" message. To resolve this, restart the computer and try again.
Ensure that the Safe mode option is selected.
Press Enter. The computer then begins to start in Safe mode.
When you are finished with all troubleshooting, close all programs and restart the computer as you normally would.

OK I have sorted the booting up problem, my monitor decided to stop working at the most inappropriate time!!

I have now tried removing the fs9.cfg file, but when FS tries to start it is unable to write a new cfg file and comes up with the message of the FSSound.dll being incompatible.

I have repaired and installed the latest version of DirectX.

I have removed three Navlog files (which I believe is what you was referring to?) and yet again FS is unable to create a new one.

I have been onto the Microsoft website and followed about 8 steps which they suggest.

I am still getting absoloutely nothing. The FS splashscreen appears and then after a few seconds it disappears.

Any other suggestions?

Go into the root (main) file and remove the FSSound.dll to your desktop.
If it still doesn't start, delete the log file.

I have just done a restore to a couple of weeks back, and hey presto it has finally started. I now however have to do some testing to see if everything is as before.

I have decided to do a complete backup of my flight simulator, but I know FS puts files everywhere. Has anyone ever done a complete backup (with paid add-ons etc) and can you tell me where all the folders/files are that I need to backup?