Comments for IE 6 no longer work?

Recently I can not connect comments for IE 6 in html-code. It seems that something happened.

Previously, he confidently used constructions like:

<! - [if IE]>
According to the conditional comment this is Internet Explorer
<! [endif] ->
<! - [if IE 5]>
According to the conditional comment this is Internet Explorer 5
<! [endif] ->
<! - [if IE 5.0]>
According to the conditional comment this is Internet Explorer 5.0
<! [endif] ->
<! - [if IE 5.5]>
According to the conditional comment this is Internet Explorer 5.5
<! [endif] ->
<! - [if IE 6]>
According to the conditional comment this is Internet Explorer 6
<! [endif] ->
<! - [if IE 7]>
According to the conditional comment this is Internet Explorer 7
<! [endif] ->
<! - [if gte IE 5]>
According to the Internet Explorer 5 and up
<! [endif] ->
<! - [if lt IE 6]>
According to the conditional comment this is Internet Explorer lower than 6
<! [endif] ->
<! - [if lte IE 5.5]>
If Internet Explorer is lower or equal to 5.5
<! [endif] ->
<! - [if gt IE 6]>
According to the Internet Explorer this conditional commental is greater than 6
<! [endif] ->

However, since then, IE 6 has stopped responding to comments related to it. I decided at first that I had incorrectly inserted comments, but today I noticed that on a previously working project, too, such comments now stopped working.
Anyone know what happened?
By the way, I build in XHTML 1.0 Strict
UPD. In vain I spread panic seems. Something happened to my browser, it seems, on the other machines everything works :(
UPD2. Glitch was with Multiple IE. Explanation and fix here .