Can't turn off transparency.The usual settings to change it don't work

Hi. I've read lots and used lots from this forum - thanks! - but first time posting here. I've searched, but haven't found a similar issue to this.

My issue:

I was using Aero with no problem. I had customized it a little, but only basic things through the Personalize section of Control Panel. I turned off transparency, and it worked perfectly.

I downloaded some themes from different sources (deviantart, etc). They were full themes that changed dlls. I tried them for a while.

Recently I switched back to my normal slightly-customized Aero theme. Everything from my theme is back and working correctly.... except opaque window tops.

Now when using my customized aero-theme, I can't turn off the transparency of the top bar of open windows. It affects all applications: Explorer, Firefox, Skype, etc...

Here's a snapshot of how it looks:


In this example above, the Control Panel is on top, but through it you can see Firefox... and through Firefox, you can see the desktop. It's a mess to figure out where one window ends and another beings, so clicking, dragging, sizing, even reading it are all a hassle.

I want to disable that so the tops of the windows are solid, but I can't make it solid and still keep aero peek.

Steps I've tried:
- in Control Panel\Appearance and Personalization\Personalization, I unchecked "enable transparency."

- in Performance Options, I turned off everything that could be causing it. Here's a shot of my current settings:


- in the registry, I confirmed that Colorization Opaque Blend is set to 1 (=disabled). Here's a copy of the DWN settings in the registry:



None of this works. I tested the theme "Windows 7 Basic". It successfully made the tops of the windows opaque. However, it doesn't have aero peek, etc, which I want.

Any suggestions on what I must change to make my customized-aero theme disable transparency again and have opaque window tops?

Thanks!

Hi Bongo. Thanks for the suggestion to run the system file checker. It worked. I ran it first to verify. The log file was enormous and I couldn't make heads or tails of it, so I just closed my eyes and ran the sfc. Restarted.. and my windows are no longer transparent. If I click on the transparent checkbox in Personalize, they become transparent, and if I uncheck that box, then my windows are opaque as they should be. No idea what it actually did... but problem solved. :) Thanks!