>Yes, but I'd wager most home PCs are set to Automatic Update

But most PCs are corporate, so are likely to have their patches applied at the same time thanks to a site or company wide policy.

I think the note from skype is only half the story - yes, the multiple simultaneous log-in attempts must have meant that nodes were overloaded, which made for a slow "start-up", but there have been many patch tuesdays and none of these have caused this supposedly "4-year-old" problem.

Explain also the release of a new client on Friday? If this was a central algorithm issue why would this be needed?

The issue has to be the content of the patch in question - why skype are holding back on admitting this is interesting to say the least. You'd think it would be in their interest to blame Microsoft - especially with their "Live" competing products now available...