McAfee DAT 5958 False Positives disables Windows from booting
While many companies and individuals avoided impacts with DAT 5958, it was a serious one as it disabled a key Windows service and PCs would not boot in normal mode. CNET earlier quoted an estimate of a 1.5% impact, but I believe McAfee eliminated that from the referenced post. Later MSNBC, noted security experts estimating a 10% impact which is more likely
McAfee blog entries on DAT 5958 issue
McAfee CEO comments
McAfee resources on DAT 5958 issue
CNET Article reported an initial 1.5% impact
MSNBC article reflects possibly 10% impact
QUOTE: The big problem is that in most cases it can not be done remotely. Someone has to walk up to the affected system, reboot it in safe mode, apply the fix, and reboot it again. This can take a long time if the systems are not close to each other, or if there is only limited onsite staff."