Hi
a lot of problems here could happen due to missing or corrupt files. The latter is very very rare. However the former could happen often by running registry cleaner software. A lot of registry cleaner software are not very well written for all kinds of system. They release the product without properly testing. Be extremely careful while deleting the registry keys with Ccleaner! It is better not to clean the registry with Ccleaner. I have been using Tune Up to clean the registry which is excellent in cleaning the registry with its 1-click maintenance. There are a lot of registry clean/boost software, don't use them!
If you know how problems could happen generally to BD engine, please mention.
Hemanth