McAfee Antivirus deleted imagehlp.dll on install slowing down OE so much that it would take minutes to open, and also affecting online forms in IE. More recently, McAfee has confirmed that its antivirus programme causes kernel32 errors (as at V5.1). 

McAfee VirusScan Causes Performance or Hang-up Issues [Q268113]
http://support.microsoft.com/support/kb/articles/q268/1/13.asp

The problems with McAfee really are never ending <sigh>

IExplore Caused an Invalid Page Fault in Module MCSCAN32.dll
http://support.microsoft.com/support/kb/articles/q300/0/28.asp
 

There have also been MANY MANY reports of McAfee's email scan and auto-update facilities corrupting Outlook Express's data folders (*.dbx) causing massive loss of email, particularly the inbox folder.  If you must use this programme, make sure that OE is NOT set to go directly to your inbox when opening.

McAfee have admitted there is a problem, and is referring its users to an MVPs rescue utility called DBXtract:

http://www.mcafeehelp.com/faq.asp?docid=60743&CategoryId=269&chat

If you have been unlucky enough to have lost your emails thanks to McAfee, there is a good chance Steve Cochran's DBXtract utility will save the day.  You can find this wonderful little programme here.

McAfee now says it is not necessary for OE users to use email scan.  Here's what they said:

"You don't have to worry about the e-mail scan as this is a corporate feature -requiring Outlook 2000 and a mail server such as Exchange server. Unless you meet the criteria you should make sure that it is disabled. As long as you have the Download scan and Internet filter enabled you'll be just fine as these two options effectively checks anything
downloaded -including e-mails. I hope this answers your question. Remember e-mail scan is for corporate users only".
 

VirusScan can also slow down the right click speed in IE. Check out this link to my FAQ on this issue.

McAfee Safe 'n' Sound causes problems when downloading...

File appears to be downloading but is not
http://support.microsoft.com/support/kb/articles/Q301/7/16.ASP
 

Next some more Knowledge Base articles:

Error Message "Iexplore Caused an Invalid Page Fault in Module Kernel32.dll" When You Close an Internet Explorer Window
http://support.microsoft.com/support/kb/articles/Q276/4/59.ASP

You Cannot Change the Temporary Internet File Folder or the Cache Size (Q301897)
http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q301897
 

OLEXP: Windows Me Hangs, Task Mgr Cites Msimn When You Close Outlook Express [Q297225]
http://support.microsoft.com/support/kb/articles/q297/2/25.asp

OLEXP: Outlook Express Performance Is Slow [Q271510]
http://support.microsoft.com/support/kb/articles/q271/5/10.asp