The other day, Rafael of WithinWindows fame discovered a weird bug in Windows 7 that causes all MSI-based installations to fail. Chris123NT wrote it up, describing it as an SQM (part of CIEP, the internal feedback program) bug:

Many users have started experiencing random crashing of explorer and msiexec.exe when trying to start Windows Update or install anything that uses an MSI based installer.  This issue is bad enough that some people have even formatted because of it, only to have it come back again.

Rafael has discovered that the fault lies with the SQM Client which is part of the Customer Experience Improvement Program.  It seems that ANY process that calls WinSqmStartSession in ntdll.dll will start crashing when MachineThrottling is enabled in the registry, which seems to happen as a result of CEIP running.

There are two workarounds for this issue.

Bryant at AeroXperience followed this up with an editorial of sorts ...

Until this is all resolved, if you’re a beta tester, please kill the CEIP in Windows 7 and proceed to report any UX quirks you run into through the submit feedback tool next to the minimize button in the titlebar of every major window.

And even Mary Jo Foley got in on the act.

Bryant and I had an IM exchange about it this afternoon and he noted that it needs to be publicized. I agree with that. But. Is it a SQM client bug?

Not necessarily. Rafael tells me that ...

Chris and I both reported this bug to Microsoft as part of a team effort. (The beta program has started "team-based bug reporting.") With regards to the problem, all I know is the fault lies within ntdll.dll, in a function named WinSqmStartSession. The SQM API is naturally undocumented so it is unclear as to what the exact problem is at this time.

It was noted that upon process execution, renaming the registry value works. It's a bit of a stretch to claim "Machine Throttling" is the cause of failure here. I will investigate it further.

Regardless, something is going on. I'm curious to see what Microsoft has to say about this in the coming days.

UPDATE: Microsoft has already provided a "fix" for the bug, which is acknowledges is "an issue with the Customer Experience Improvement Program (CEIP) client in Windows 7." It will be trigger via the Windows 7 Action Center, naturally.  Thanks to everyone that wrote in about this.