I've had this problem in several installs of Windows 7 x64, including this current fresh one. It usually happens about a month after a fresh install.
Here are some facts about the problem:
1. The only icons affected are .mht, .htm., & .html.
2. File extensions are fine - no issues.
3. .mht = Internet Explorer ... both htm & html are associated with Firefox.
4. In Firefox, when using "Save Page As", in the Explorer window that opens, the icons are always there! This has been true in each install of Windows 7, though after a year or two they will sometimes not appear in this case as well. Then, they'll suddenly reappear.
5. Rebuilding the icon cache didn't fix it.
6. Changing the file association temporarily didn't work. When changing htm & html to IE, the icon appears. But changing mht to Firefox doesn't cause an icon to appear, not does the correct IE icon appear when I change the association back to IE. Changing htm & html back to Firefox doesn't work, either.
7. No custom icons, file extensions, etc. are involved.
8. Other icons in the same Explorer window .. DO appear, without fail.
Would appreciate any help for this annoying problem. Below is a screenshot.
Thanks is advance.