Any problems with downloaded files/planes???

[IKEpod]

well, I have so far downloaded and installed 50+ planes, changed panels, added instruments, never had a problem...
But after downloading this file FSX iFly 747-400 Package V1.1.0.0 I had massive problems with FSX. it would not start.
Another download, the 777 package does not work either. Cockpit does not appear working.
The FSX Tupolev TU-144 when compared to the Concorde is a poor plane. 2D panel works  only partially.
Funny story about the A380 800... I downloaded the plane as soon as it was available, and it worked and flew fine. After a few weeks, the plane does not even appear in the aircraft list... ?

Anyone who can help a flying enthusiast (real and virtual AC).
Thanks
IKE