I have Direct X 11 installed, but when I try to play D&D online through Steam, I keep getting a message that says I need the most recent version of Direct X.

I've lately had a lot of lag issues with games I've never had issues with before, both offline and online, so I'm not sure what is going on here.

I also tried running the Direct X installer and get the following error:

"An internal system error occurred. Please refer to DXError.log and DirectX.log in your Windows folder to determine the problem."

But I go to the Windows folder and I don't see those anywhere.

Any help would be greatly appreciated.

Try reinstalling DirectX 9.

Can't. That's when I get the "internal error" message, which causes the installation to fail.

Not even sure how you do this, but uninstall and reinstall?

Try using the full US version which can be downloaded here.

Make sure you right click the directx_Jun2010_redist.exe and click "Run as administrator" on the resulting dialog.

To have a potentially more accurate diagnostic, use "Windows key+R" and type dxdiag (then enter, obviously).
You can run diagnoses there and see what's wrong.

Ok, about to give that a shot. It doesn't come up with any problems. Grrr.

Oh yeah, I'm blind and can't read past the first few lines apparently. Sorry about that.

Just finished the chkdsk thing, but it finished before I saw the end.

Anyway, came back and my OS was booted up, so now it's time for some testing.

... Wow, so far it seems everything has improved! Awesome!

And now it's screwy again.

I tried the same solution, but this time it didn't work.

Nothing is affected but Steam, so it's not going to kill me. It's more frustrating that they operate DX the way they do; it's unnecessarily complicated. I've done searches and tons of people have the same problem, but at this point I think I'll just forget about it. I've wasted enough time trying to figure it out!

Your issue probably has nothing to do with installing the optional files... why do people keep confusing optional files with DirectX installations that happen only through applying a service pack is beyond me. And no, its not complicated.

Anyways, open Command Prompt or Powershell and do:

sfc /scannow