Memory could not be read/written errors in IE 6 when hyperthreading enabled

I am having a lot of trouble with Internet Explorer 6.0. I keep getting an error message saying: The instruction at "0x0157d43d" referenced memory at "0x2f7a6e2e". The memory could not be "read" (these numbers vary, and has a few times been “written” instead of “read”). Quite often when I’m loading any page, like Amazon.com, I find that all the images won’t load and come up as boxes with red crosses inside. While the page that has the problem is open, I’ve checked Task Manager and have found IE is suddenly using around 50% of my 2.8GHz cpu. Sometimes it will go on using 50% cpu, even after the browser’s closed! When a web page becomes like this, with images not loading, I find that I cannot load any other pages in favourites (or any web address I type in), until I close the browser (which causes the error message) and open a new one. I have cleared Temporary Internet Files, Cookies, and have run Spybot, Adaware, CWShredder and Norton Antivirus full system scan. I have even tried an in-place reinstallation of Windows XP. Other people have had this error before, but they usually have the option to press ok to terminate the program, or cancel to debug. I can only press cancel to close the error box. If I disable hyperthreading for my cpu in Bios, the errors no longer come up and iexplore.exe doesn’t ever get stuck on 50% cpu usage. After disabling HT, only the occasional web page that has tiny images (button icons, etc.) will appear as boxes with red crosses inside at much less frequent intervals but the browser no longer crashes. I don’t want to leave hyperthreading disabled, and have had it enabled for months without problems up until now. I would appreciate any help.

System Specs:
ASUS P4S800 motherboard, with latest BIOS revision 1009
Pentium 4 2.8GHz
1024MB ram
Windows XP home