Strange FS9 behaviour?

For sometime now I have been getting problems loading variousUK and other airports in FS9. The loading stops at anything between 9% and 13% in the loading terrain sector. Fed-up with this I decided to remove all scenery entries (724) and add them again to the scenery.cfg 10 at a time. Will give youa couple of examples of what I found.Problem with loading UK airports mainly occured with all airportsexcluding those in Northern Ireland. After employing the abovemethod I found that the culprit was an addon scenery for Canberra(Australia) but couldn't find anything inside those folders that I couldrelate to the UK. Likewise my LEMD scenery was not loading properly either butafter again using the above method found that another addonscenery this time in France was causing the problem.Question is, why would sceneries for different parts of the worldaffect other sceneries which geographically speaking are nowherenear each other.While on this subject would appreciate some feedback/opinionson whether or not it is advisable to use either a Memory Manager(MaxMem, etc) or a Cache Manager (O&O Clever Cache)with FS9.Thanks