Referring to your first post. I don't think it is a problem connected with updates. I have several different versions of Windows 7 installed around the premises, all official (Technet) I install, automatically, all updates offered except drivers, which I choose carefully. Since the later beta build releases, I have not had any malfunctions, other than those of my own making.
I use the "Check for updates but let me choose whether to download and install them" This gives me the option to examine them firsthand, before making that choice.
I think there have only been, so far, 4 updates to Windows 7 alone, (Many others, but related to MS software I own) none of which would have interefered with IE8.
However, the following updates have been issued on the automatic function, for IE8. Perhaps, if they have been reinstalled without your knowledge, you could try uninstalling them one by one, the newest first of course. If succesful, you could then "hide" the offender so that it does not reinstall?
Update for Internet Explorer 8 for Windows 7 (KB976749)
Installation date: 01/12/2009 09:36
Update for Internet Explorer 8 Compatibility View List for Windows 7 (KB975364)
Installation date: 01/12/2009 09:36
Security Update for Internet Explorer 8 for Windows 7 (KB974455)
Installation date: 01/12/2009 09:33
If all does not improve, you could also go into the "Tools - Advanced" and reset all the IE options.