Could not load library (4)

Please check the properties of 7+ Taskbar Tweaker. Does it run in a compatibility mode on your computer?

I'm anon.
No, no properties are set. Even setting to "Windows 7" alone didn't get the trick too.

In general, error 4 means that the injection failed.
Specifically (in case you have some WinAPI knowledge), it fails to call the GetProcAddress function, probably because the address is different in the tweaker's process and in the explorer's process.
I don't know why that happens. I know it can happen when enabling compatibility settings, but you've said that yours are disabled.
You say that the issue started after updating NVidia drivers. Could you try disabling, or temporarily removing them, and check whether they cause the issue?

Great answer. I'll run some tests and come back to report you.

Got it to work!

The issue is caused by a program called I n k S a v e r who runs at startup installing itself under HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run. Didn't go deeper but happy cause I found the culprit.

Putting 7TT startup entry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run to make it run before that program does the trick.

I know this is not the correct approach to solve this, but, i'm the lone user on this machine. And works like a charm.

I checked it, and could reproduce the issue.
The problem is indeed caused by the InkSaver program. It injects code into the 7+ Taskbar Tweaker process (among others), and hooks the GetProcAddress function, which breaks the injection. I think you should report it as a bug to InkSaver, especially if you're a paying client of theirs.

Tweaker v4.5.4 inactive - use it to show desktop. On boot get <Error 102>, Taskbar Inspector says, <not intected into explorer>

Please see my reply here:
http://rammichael.com/7-taskbar-tweaker/comment-pa...