wmvcore.dll

I've just updated my Winows Media Player 8 to version 10. After the installation my internet speed has been halfen! So I used a program called "Total Uninstall 3" to clean out all the newly created registry & files. After that my internet speed is all fine again, but my Winows Media Player 10 can't play any *.wmv or *.mp4 files, except for *.avi files

So I used Process Explorer to do a checkup on the problem, I learnt that the "wmvcore.dll" is not being updated through the Winows Media Player 10 installation, the "wmvcore.dll" is still a version 8 & not a 10. I've try to reinstall the Winows Media Player 8 & 10 many times over & still it couldn't solve the problem, the installations just won't update the "wmvcore.dll" to version 10.

So I went to my second PC in my house, it's also a WinXP Pro, but it has a "Winows Media Player 8" running on version 10 "wmvcore.dll" (& it actually worked because the version 10 "wmvcore.dll" included the version 8 registry in it)

So I copy the version 10 "wmvcore.dll" from the second PC & ported it over to the troubled PC, it does solved the problem, but the Winsno Media Player 10 has a problem of playing the *.avi file in a new (isolated) media window other than within it's main screen! it doesn't do that to other file formats such as *.mpg or *.wmv ...

Anyone knows how to fix that? thanks.