OK.. Reinstalled DX9. Fixed it.
Still, such a utility would be good.
And, i still have the problem i had before unregistering stuff (AVI Splitter, pff what am i mad??

)
Every time i close a video two application errors occour.
CODE
The instruction at "0x027abd9b" referenced memory at "0x02924330", The memory could not be "read"."
Click on OK to terminate the program
and
CODE
The instruction at "0x027aa8a0" referenced memory at "0x02923ef8", The memory could not be "read"."
Click on OK to terminate the program
I have no idea what causes the problem.