IE6 visitors are actually bots, from Microsoft.

[JAB Creations]

Microsoft apparently owns this range of IP addresses: 157.48.0.0 to 157.55.255.255. Analyzing visitors using Internet Explorer 6 about a quarter to a half of them originate from this IP range (subjective to the usual array of traffic related variables). These are computers where the browser is being automated by a bot, it's ultimately a bot though. The big question is if Microsoft is trying to get people to stop using Internet Explorer 6 why would they be running bots using that browser? It makes no sense.

- John

[Dijkgraaf]

Only someone at Microsoft might know the answer to that.

Some theories thrown out at random
1) They have forgotten to update these particular bots UA
2) They are testing to see if websites serve up different contents based on UA.
3) They are checking to see if sites contain malware targeted to IE 6.