I've been running into issues with Windows Update, which I can't seem to fix. The hotfixes don't work, nor does the Windows update readyness tool, or the manual SP1 upgrade. I get various esoteric errors which nobody seems to have a fix for. Looks like some of the update cache is corrupt and digital signatures seem to be broken on some packages / Windows Update components.

Long story short, I have discovered the only option is to do a repair operation on the OS, to repair everything. It's so corrupt that only a complete replacement will fix it.

According to various sources (including MSKB) one can perform a repair by running an in-place upgrade.

I've got the Windows 7 Ultimate retail disc, which I've inserted into my machine. I ran setup.exe and went through in the following order:

• Install now
• Go online to get latest updates (I've also tried not getting updates)
• Wait for updates to be downloaded
• Select Windows 7 Ultimate (x64 architecture) and click next
• Accept the T&Cs, click next
• Click Upgrade

At this point it spends a minute on the "checking compatibility" screen, after which I get the following error:

The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue.

• You can’t upgrade 64-bit Windows to a 32-bit version of Windows. To upgrade, obtain a 64-bit version of the installation disc, or go online to see how to install Windows 7 and keep your files and settings.

• 32-bit Windows cannot be upgraded to a 64-bit version of Windows. To upgrade, obtain a 32-bit version of the Windows installation disc.

It also mentions a warning about potential conflicts with a storage driver and VS2010, but that doesn't seem to be the blocking issue.

My currently installed version of Windows is Ultimate 64-bit (absolutely sure of this) and the disc is definitely a x86 / x64 combined Ultimate retail disc. There seem to be a few people who have run into this (e.g. this question), but I've not seen any answers. I've checked the event viewer, but can't spot anything in there that's related.

Any idea how I can get this working?

P.S: Just to pre-empt the inevitable "are you suuuuuuuuuuuuure it's x64 Ultimate?" questions: