Wininet.dll

I'm getting an invalid page fault caused by this file (although I can still explore the web page with the same window, go fig) and I'd like to replace it. I D/Led an exe that will replace the file, but when i do I get an error saying the file is in use and can't be replaced. What can I do? I've already tried copy pasting the file in, and deleting the original before dropping in the new file.