Strange comments in Firefox

I used vs2008 as a small forum system and used it in IE7 all the time. Today I suddenly used Firefox to show the effect and found a problem on my webpage, open the source file and you will find a lot of HTMLCodeCommented out.

My code is like this:

<! ------- Comment ------->

Code 1

<! ----- Note ------>

<! ------- Comment ------->

Code 2

<! ----- Note ------>

<! ------- Comment ------->

Code 3

<! ----- Note ------>

The strange thing is that not all codes are commented out, but some are commented out and some are displayed normally. I am very depressed.

I don't know if a friend has encountered such a problem. Please help me solve it. Thank you very much.