A not quite invisible file?

[rmmccoy]

I was installing a program and while I haven't tried it yet, it seemed to install okay - except for the other message that the program couldn't start because of a missing file, namely "mcf100.dll". Jumping to the end of the searching, the file and a number with similar names (e.g. mfc100rus.dll) turned out to be in both system32 and SysWOW64. However, after using a couple different search programs I discovered that a search starting in Windows as the root would only turn up the mfc files in SysWow64. The attributes, date, and size come up the same regarding of which files I compare. If it makes any difference, this is a SSD.

Questions? Suggestions? Know any good witchdoctors?

 

[LMiller7]

I think you are seeing the results of file and folder redirection, a normal operation in 64 bit Windows.

In 64 bit Windows 64 bit system files are stored in the system32 folder while 32 bit system files are in syswow64. There are valid reasons why it was done this way, But no make things work for 32 bit applications more must be done. Older 32 bit applications would not be aware of syswow64 and in a 32 bit OS it didn't even exist. To make things work when a 32 bit application requests a file in system32 it is silently redirected to syswow64. 64 bit applications are not redirected.

The end result is that 32 bit applications work the same as they did in a 32 bit OS. Many users are unaware they are even using a 64 bit OS or if it matters.

Many files in system32 have 32 bit versions with different sizes in syswow64. In some cases there will only be a 32 bit version in syswow64. A 64 bit search program would see one or both exactly where they are.

But due to redirection a 32 bit search program may see things differently:

1. If there is only a 64 bit version it will look in system32, be redirected to syswow64, and see nothing. It will look in syswow64 and also see nothing. It will not see the file at all.

2. If there is only a 32 bit version it will look in system32, be redirected to syswow64 and see it there. It will look in syswow64 and see the exact same file again. It will report the file as found twice.

3. If there are 32 bit and 64 bit versions of the file it will look in system32, be redirected to syswow64, and see it there. It will look in syswow64 and see the same file again, the 32 bit version.

A 32 bit search program that is 64 bit aware can temporarily disable redirection and see things just like a 64 bit program would. But if the developer is not aware of the complications of redirection, or the program predates 64 bit Windows, this will not happen.

To avoid the potential confusion it is best to use only 64 bit search programs in a 64 bit OS.