Windows Update oddity re KB2510531

I just performed some selective Windows updates yesterday, installing some and holding off on others per recommendations from Woody Leonard's site as well as Susan Bradley's "column" in the "Windows Secrets" newsletter. Before I downloaded or installed any of the updates, I printed out a list of available updates.

One of the updates on this list was "Security Update for Windows 7 for x64-based Systems (KB2510531)". I chose NOT to install this particular update at this time.

After installing the desired updates and rebooting, I checked the Windows Update site for a list of the remaining updates. I did not see the update KB2510531 listed.

Odd, I thought. Perhaps I had installed it unknowingly? I checked my Windows Update history and did not see it listed there either. Feeling a bit confused, I then went to Programs and Features (FKA Add/Remove Programs), and told it to view installed updates. It wasn't shown there either.

OK, maybe somehow it got put into Hidden Updates by Windows Update? Nope, also not listed there (I had NO hidden updates).

I also counted up the number of updates on my printed list mentioned above. The number was 26. I then counted the number of updates I had installed per the Windows Update history (16) and the number of updates remaining to install per the Windows Update site (9), which totals 25 - one less than the number of updates on my original printed list. Makes sense since KB2510531 is missing from both of the current Windows Updates lists.

FWIW, I had installed the IE8 security updates in the first wave and installed IE9 in the second wave of updates that I did yesterday.

Does anyone know what the explanation is for security update KB2510531 not currently showing up on any list? It looks like it just disappeared!

No, I did not install SP1 yet. That's one of the updates I was holding off doing.

I found out via the Windows Secrets Lounge site that installing IE9 makes this particular update unnecessary.