I'm trying to clean up an old Windows XP machine that had malware on it. I ran a "quick scan" with Microsoft Security Essentials, which found and removed one "threat."  However, I still have a problem....
When using IE8 to navigate to the download page for Adobe Reader, the tab crashes and I'm told that "A malfunctioning or malicious add-on has caused Internet Explorer to close this webpage"  Consistent with this, if I start Internet Explorer without add-ons (
-extoff command-line option), then I can load that page ok.
But if I use the "Manage Add-ons" window to disable every extension I can find , and then start IE normally (without
-extoff) and navigate to that page, it crashes again!
I don't understand this. Could this crash be caused by some "hidden" extension that doesn't show up in the "Manage Add-ons" GUI, but is disabled by the
extoff command-line switch? If so, how might I find it and remove it?
For the record, I've also tried "Reset Internet Explorer settings" (Internet Options > Advanced > Reset) but the tab still crashes.
 Before that, I ran TrendMicro's "HouseCall" tool but it found nothing. Am currently running a full system scan with MSE. Also have access to McAfee VirusScan, so I'll try that next.
 The full error message is long, but you can see it in IE at
res://ieframe.dll/acr_depnx_error.htm DEP is turned on system-wide (Control Panel > System > Advanced > Performance > Settings > Data Execution Prevention > "Turn on DEP for all programs...") If I turn off DEP, then instead of getting that message when loading the page, IE just freezes completely.
 To disable "all" extensions, I did this: IE > Tools menu > Internet Options > Programs tab > Manage Add-ons. There's a drop-down menu on the lower-left labeled "Show:". For each drop-down menu item there, I selected all the extensions listed in the right-panel, right-clicked and chose "Disable All."