A recent example of a debugging episode with IE6 –
We recently discovered that a form on a certain website had mysteriously stopped working in IE7 and Firefox (2 or 3, I don’t know which version) on a PC. More specifically, something was preventing the user from clicking on the form fields and links on the page. After re-creating the issue in IE7, and finding that certain links to the far right of the page were still clickable (as if an invisible box was hovering over most of the page), I started commenting out some CSS code, and found the issue was with some PNGs I was trying to force IE6 to see as transparent using the alpha channel filter fix hack.
This fix usually works well on background images (if you’re not putting a link on top of them – links don’t work) however, if you use a form on the same page, it will interfere with the way the form works – i.e. – prevent the user from entering information into the form fields – in essence, the form doesn’t work. There is a fix (see #8 in a list on the page linked above), but instead I decided to just re-engineer the page and not use the alpha channel filter fix hack at all.
Just another reason why IE6 users should at least upgrade to IE7, and ideally just move to the more secure, standards-compliant Firefox browser – the ways in which IE6 limits the progress of the web are numerous.