Jetfytrfan I am certain you have more than 90 airplanes in your in aircraft folder. Remember that your aircraft folder number of planes also include AI planes that may not being showing up when start the program. In another word when you strat the game and you go to free flight and  count the number that you may chose. The number add to less than 90. Well that does not mean that you have less than 90 in your aircraft folder. The best solution for that to is make a separate folder and name it aircraft 2. Place all the planes you are less likely to use with the copy and paste procedure in it . Do not go crazy and copy and paste to many . Just eigth or ten would do. After that try to reopen the MB. Remember to  do this only to addon planes since without the stock plane the program wiil not work.
If that does not work . You can always reinstall that pragram. Do not bee afraid that you will lose any of you previouse information. That will not happen. When reinstalling do click on Media before you strat reinstalling . You will see it when you start the reinstall procedure. that way you will able to keep the previuse installs you made. Do not worry I done this many times with excellent result.

Another word of advice. If have any problem. You can always go to the secound page on this forum. You can look up on How to improve you CFS2 experience Tips. I and  many others will give tips on to improve you understanding Cfs2 and improve you expereince.

I hope I have been able to help you a bit. I do not have all the answers . but I not mind help you out. Their are other with even more knowledge than mine that that are also willing to help you out.

I would like to hear from you . Iam intersted if this Post help you in anyway.                                            james007

Thank you gentlemen for your suggestions. I found that my problem was not the number of aircraft rather it was the freakin windows patches causing me to lose information when restarting my pc ( used to think I had to restart after every group of installs). Something so small as clicking on "cancel " instead of  "end now". I reinstalled, deleted every empty folder and then installed my 3rd party aircraft. I'm good to go now.