If I have "Enable VT-x/AMD-V" ticked under Settings/System/Acceleration, I get an error message "Windows protection error. You need to restart your computer" whether I try Normal or Safe Mode from the Windows boot menu. If VT-x/AMD-V is disabled, if I try selecting Normal mode there is no "protection error" message, but Windows still fails to load to desktop, showing just a black screen with a blinking cursor; Windows will only load to desktop in Safe Mode.
I have tried searching around online a bit and there is some mention of an old "too-fast AMD CPU" bug, but most of what I've read suggests that the bug and associated patch applied only to Windows 95 versions, and not Windows 98. Is it still the same bug, or something else; is there anything to be done or am I stuck? I'd rather not go around patching things blindly (or even diddling values in a hex editor, as one page suggested!