Well, I thought I had solved this problem by re-installing PSE 8, since it worked again for a while. However, now inexplicably it has started having the same problem again (i.e., refusing to get past the license agreement screen even though I click "accept") - see this thread for the first part of this problem/discussion:
http://forums.adobe.com/message/4823143#4823143
This time, after trying all the suggested solutions without success, I again tried to just go ahead and re-install PSE8 to solve the problem. HOWEVER, this time I keep getting an error message during the attempted installation (actually, during the beginning part where it makes you uninstall PSE8 before it will install it again) that prevents the installation from completing. The error is shown below: