Strange icon replaces others

[Clangor]

For a couple months now, in XP, the icon for every .url file is an icon of the letter G in an orange callout, and the same icon is an overlay over any file on an optical disc when viewed with Windows Explorer.  I have no clue why this happens.  Does anyone have a guess?

[Clangor]

Here is another example, where it replaces the icon associated with .url files, and doesn't allow it to be changed back.

[patio]

Did you experiment with a new browser ? ?
Is there a program on that machine that you recognise that logo from ? ?
Who is your ISP ? ?