IE 8 Security Settings Disallow Downloads from Trusted Sites

IE 8 keeps blocking the downloading of executable files (and others) due to
my security settings. I've tried almost everything suggested on another board
to fix the problem but it won't resolve. I've tried booting IE 8 in "no add
on" mode, but that didn't help. I've clicked on the security tab under
"Internet Options" and toggled the security setting bar to its lowest
allowable setting for Trusted Sites to no avail. I've clicked on the "Custom
Level" button and tried to reset "custom setting" to "Low", but everytime I
click OK and close the window, it goes back to the default setting of
"Medium-high." I've looked over all of the individual custom settings in the
window above the "custom setting reset" button, but am not expert enough to
know which individual settings to change. I tried to enable dowloads without
prompts, but that did nothing to fix the problem, and I don't want to fiddle
with other settings when I don't know what they do.

One thing I have NOT yet tried is clicking on the "Advanced" tab under
"Internet Options" and choosing to reset IE 8 to its default settings because
of the warning that I should only do this if the browser is in an unusable
state, which it is not, at least not yet until I put my foot through my
monitor, which is about the be the next thing I try. I keep thinking there
must be a simple fix to this problem, but so far it has eluded me. Whoever
gives me the correct answer gets a gold star! Thanks in advance for your help.

P.S. Someone on another board suggested that I may have a corrupted user
profile, but he thought I was running Vista and not XP Service Pack 3. I have
XP. Can this be a problem in XP as well? If so, can anyone direct me to a
How-to on fixing a corrupted user profile in XP?