You can just ignore it if it's not too confusing for you. Thing is, Windows is glitching, not Norton SystemWorks. There's a little unsupported Microsoft program called Tweak UI that has a fix you can run whenever it happens. Here're the links:
Tweak UI 1.33 for Windows 95, 98, 2000, NT, Me (After you install it, run Tweak UI from the Control Panel, then go to the 'repair' tab & click Rebuild Icons)
Tweak UI for Windows XP (I haven't used the XP version so I can't help you here)
Able2Know losing it's icon in your IE favorites list is an unrelated problem, as far as I know. From personal experiance Internet Explorer doesn't usually hang on to those custom icons in the favorites list for too long & will often revert back to the IE logo. Not much you can do about it. Other browsers don't show the custom icons anyway.