rundll32.exe application not found question

Hi.

My netbook keeps showing the error "WINDOWS/System32/rundll32.exe Application not found".

I did research and I have to replace the broken rundll32.exe file with a working one.

All my other healthy computers are Vista though, and i don't have Windows on a usb to try and fix it that way.

Is it ok to try to replace the rundll32.exe file with one from Vista instead of XP?

If not, do you think it's safe to download a fix from the internet? (http://www.dougknox.com/xp/file_assoc.htm)

Thanks.