Comments for IE 6 no longer work?

Recently, I can’t include comments for IE 6 in html code. Something seems to have happened.

I used to use constructions like:

According to the conditional comment this is Internet Explorer


According to the conditional comment this is Internet Explorer 5


According to the conditional comment this is Internet Explorer 5.0


According to the conditional comment this is Internet Explorer 5.5


According to the conditional comment this is Internet Explorer 6


According to the conditional comment this is Internet Explorer 7


According to the conditional comment this is Internet Explorer 5 and up


According to the conditional comment this is Internet Explorer lower than 6


According to the conditional comment this is Internet Explorer lower or equal to 5.5


According to the conditional comment this is Internet Explorer greater than 6

However, for some time now, IE 6 has stopped responding to comments related to it. At first, I decided that I had inserted the comments incorrectly, but today I noticed that on the previously working project these comments also stopped working now.
Does anyone know what happened?
By the way, I am installing in XHTML 1.0 Strict
UPD. In vain I started a panic seems. Something happened with my browser, it seems,
maybe everything works on the other machines :( UPD2. The glitch was with Multiple IE. The explanation and fix are here .