I moved this Thread to the Hoster Help Forum, changed the title, and edited the posts to reflect what I perceive was done.
The fact you shut down your computer, then later powered it up and a file was missing can be wrongly assumed that Hoster (or any application program from any vendor) deleted the missing file.
Actually, we have heard that shutting down Windows can cause this. 
I personally believe that with all the updates that Windows does now, if you don't reboot after installing Windows Updates, you can loose files in the process.
You were correct to install your Windows CD and re-install it to fix the missing file. At least Microsoft has this means to "fix" deleted files working correctly!
Thanks for both of you posting. 