Your problem is probably similar to the one from this post: emachines labtop?
The only difference been that the missing file(s) is (or are) not the same.
The cure is also quite the same: Get a Linux Live CD, boot from it and backup your data, reinstall windows, reinstall your applications, restore your data.
Electro
August 2011
Automatic Answer
While you wait for answers, we may have found some information which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix desktop pcs.