Hello...
The IE vulnerability to spyware and adware is a chronic illness. You cannot cure it. You can only medicate the symptoms. You can spend a lot of your time and effort running spyware and adware scanners. Sometimes you'll have to reinstall the operating system to get rid of it.
What is the end result? Your PCs will continue to be vulnerable to the same infections.
That is precisely why I left IE. All of the systems in my company use Firefox and we don't have a spyware or adware problem. Period.
Note: We don't use Outlook for the same reason. No virus problem either.
I feel your pain. When your management gets tired of the problem, hopefully they will choose a real solution so you can work on something else. My answer provided the best one currently available.
Best of luck to you.
-----Steve Jackson
CEO/CSA
Software Corporation (Softcorp)
http://www.softcorp.us/probono
Advanced pro bono tools and utilities free for personal use