GoogleEarth doesn't recognize DirectX is installed

I'm still in the process of reinstalling my OS (XPP-SP3) on this old box after a crash, and yesterday I installed GE directly from Google. Immediately prior, I had checked WinUpdate and gotten 0s. But when I tried to run GE, it said DX wasn't installed. So I installed it directly from MS, and rechecked WU - still 0s. But when I try to start GE, it still says DX isn't installed. Trying DX again tells me that a current or later version is already installed, and it quits. DX doesn't show in Add/Remove Programs (even in CC's version), and reading the FEW old threads about DX makes me think there's no uninstalling DX to retry from scratch, so... :confused

I tried switching GE to OpenGL-mode (which made it agonizingly slow, full of errors, and unusable) and then back to DX-mode, and it still won't work. Would R&Ring GE make it recognize DX?

 

Start/run and type in dxdiag then click OK (it might ask if it can connect somewhere; say Yes)
Eventually you will get the DirectX diagnostic program.
Maybe the More Help tab can help you troubleshoot the problem.

 

It took a while to figure out their BBS setup, but I just found this:
http://productforums.google.com/forum/#!category-topic/earth/problems-and-errors/bjGnfKIW2ho

Looks like THIS ONE might not be MY fault!

But I'll still try dxdiag... Thanks!
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No faults found; all the video tests passed; I don't have speakers connected to this system, so I skipped all the sound tests. That thread suggests that it's a widespread GE7 problem for XP, so I'll just use an older version.

 

It's working! For whatever reason, "Show atmosphere" was checked by default, so initially, all I saw was a white ball with outlines. While zooming in, I could see the surface just for a moment, then it went to pale blue instead of white. I changed some navigation settings (reverse mouse zoom) and it went black. Then I unchecked atmosphere, and the surface imagery appeared. It goes white in the flight simulator, so there's still something not quite right, but at least it works.
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Narrowed it down a little: whenever the view shows the horizon, all imagery disappears.