You mean you ran the SFC after the clean install and it checked OK?
I have that file on my system. I have seen some files, as with one from Dell, that would not check during the SFC because it had been modified and was no longer the original file from Microsoft. In order to get it to work again, I believe you have to replace the .mui version so it can update the others. Do you have an original Win 7 disc or an OEM version from a manufacturer?
But you may not need to worry if it is not used. Someone suggested it is some type of language file, but I do not know.
On my 32 bit system the iassdo.dll.mui file is in the \System32\en-US folder and is 46.0 KB.
I don't have a good answer for the TrustedInstaller question except that it is an NT Service and installs and tracks the system files. Or at least something to that effect.
I did notice the power settings on this laptop allow for a sleep button setting, but I do not have a separate sleep button.