[Fix] Steamui.dll error on update / fresh install

[Goldenhelm]

There are quite a lot of topics regarding this issue on the forums already, some solved and some yet looking for a answer. I just managed to fix this issue on my new computer today and I would like to share my method, in hopes that everyone else will manage to solve their own.

Disclaimer: Most systems will probably require that you have admin privileges before undergoing these changes. Get more information regarding this as necessary.

-- Checking for the issue --
1 - Go to your steam folder > Logs > Open bootstrap_log.txt (it is generated when you try to run steam)
2 - Check for errors similar to this one:
BCommitUpdateFiles: Failed to rename |FILEPATH_| -> |FILEPATH|
BCommitUpdateFiles: Failed to process ./|PATH|

-- Solution --
Details: After trying all other fixes, I decided to navigate the folders one by one and noticed that certain files where being generated locked from the proper ownership / control settings that should be common to all steam files.
1 - Get the proper permissions for the steam folders
1.1 - WIN7: on program files folder(x86), right click the Steam folder > Click Properties > Click Security Tab > Click Advanced Button
1.2 - On the very first tab you will see a list of users and their respective permissions, click Change Permissions button.
1.3 - Check that the necessary users have Full Control permissions, if they don't, edit their permissions so they do.
1.4 - Check both boxes bellow the Add... button in order to make sure that all files inside will share the permissions that you have set up here. Press Apply button
1.5 - Delete permissions that have special effects, as these could tamper with the settings you just did. Apply once more.
2 - Run Steam again.

After this all files got the propper permissions and the Update / Install finished properly.

Sorry for the really long textwall but I tried to give as many details as possible, so that better solutions can be done or maybe the root cause found.

GL, GG