ok based on the specs you sent me, there can be several things that could cause that problem. Firstly, a GeForce 4 with 64MB should not have any problems running Microsoft Flight Simulator. However, if your view has been in the cockpit for a long time and you switch to an outside view after that, the card may not be able to catch up with processing the images as they were not mostly processed while you were in the cockpit as the panel covers most of the view. Because of the long time spent in the cockpit, your plane would have covered quite some ground and thus almost all of your surrounding would have to be processed, resulting in the image you sent me. Another reason could be that since your processor is only 800MHz, if your graphics option is set quite high, the processor wouldn't be able to 'help' out as much, putting even more burden on the card which leads to the above problem.
Another reason could be that your computer is out of ram as 128 mb of ram is considered to be little nowadays. After travelling for some distance, the scenery could have changed a lot. as your ram size is small, not a lot of textures can be stored for easy access by the card or the processor, and thus the computer would have to get it through the harddisk, which is significantly slower that the other components in the computer and resulting in a bottleneck and causes the image problem. I've personally have had this problem before but turning down the graphics setting makes most of the problem go away for me. Also the image would correct itself after sometime if you wait long enough and also if you are not travelling too fast like in a jet plane or when using time acceleration. Also the problem is especially severe if you had minimised Flight Simulator and brought it back up again. It could also occur when you pause and unpause the game. Of course it could be a combination of any or all of the factors that results in the eventual problem. Does my describtion fit your problem? If there were inaccuracies in my explanations please pardon me!

(i would add more explantions as i think of them!)
Edit : It could also happen when you zoom into and out of the plane. Using a flight model that is very detailed could also be the cause of the problem.
Edit 2 : Running intensive background programmes could also result in the problem as resources are drawn away from Flight Simuator. So try to shut down as many programmes as possible as your computer is rather slow before playing flight simulator.
Edit 3 : Also please check for software running in the background. Some of these softwares could be spywares, adwares trogans or viruses and could be hogging all the avaliable resources. Of couse some of the times it could just be an antivirus schuduled scan which happened to me a couple of times. If you are using Windows XP there is a built in taskmanager. You can just right click the toolbar and select the task manager. From there you can find out which programmes are diverting the resources. Otherwise you could download third party taskmanagers like TaskInfo that i use. To clean out viruses you could run your own antivirus software but make sure that it is updated, or use an online virus scanner such as the
Panda Active Scan and the
Trend Micro Free Online Virus Scanner. To deal with adwares you could download
Adaware by Lavasoft and for spywares the
Spybot Search & Destroy and finally for trojans the
Trojan Hunter. At the same time to free up your memory constantly, you could get
Ram Idle LE which i also use

(There are lots more free scanners and programmes out there to help you but beware of some as they may contain their own spywares or adwares to replace those that they removed!)
Here's the resized image if anyone's interested to see what the problem is

So Len is your problem the same one as this?