Zipkin blames hardware vendors for failing to strictly follow Redmond's instructions on how drivers should be installed.
"The issue is that the drivers were not written per the spec we have on MSDN to ensure successful updates," he said, a spec that "has been around since the XP days."
Zipkin declined to elaborate or comment on Sinchak's case. And neither Intel nor Macrovision, maker of the InstallShield software, immediately responded to requests for comment.
But some experts think that the problem must be related to under-the-hood changes in Vista SP1, especially those concerning security and user privileges, which can directly affect how applications and drivers are installed.
"Microsoft looks like they are monkeying around with a lot of lower-level stuff," said Paul Morris, a project manager at QualityLogic Inc., a Moorpark, Calif. software and driver testing firm. "In my mind, you've got to treat SP1 as an entirely new OS."
Vista's overhauled security model had two major changes. First, local users who were formerly granted administrator access by default are granted standard access in Vista. Second, a new feature called User Account Control, or UAC, prompts users to verify whenever a new application or driver is about to be installed.
Both moves help to prevent viruses and malware from taking hold. But UAC has been criticized by some users for its overzealousness, though UAC pop-ups decrease dramatically after the first month, according to Redmond.
Moreover, moving users to standard rather than administrator accounts wreaked havoc on many applications and drivers that depended on full administrator access to install or run properly.
If SP1 makes even small changes to Vista's security model, that could cause drivers to break again, according to Ian Lao, an analyst at In-Stat Inc. Why? For one, most vendors took the easier, less rigorous option of patching and modifying their drivers to make them Vista compatible, rather than "rewriting them from the ground-up," said Lao. That makes them more fragile.
Moreover, many drivers, unlike applications, can't be completely shut down during an installation process. The upgraded software - in this case Vista - may not be able to properly update the drivers, he said. Thus, permissions may be lost during the SP1 upgrade, or resources moved to different locations.