Well now I have something interesting, and frankly, bewildering to me.
I have made two web pages: Page A, and Page B. Both have the slideshow.
Page A exhibits the bug I described above. Page B does not, and works flawlessly.
Both pages have exactly the same code on the page, except that Page B has an additional fragment of the conveyor demo source code, underneath the slideshow. (I took away more and more of the demo source code until I found the fragment that stopped the bug.)
If this fragment is put underneath the slideshow (as in Page B), it will work bug-free in Safari, but if it's not there (as in Page A), it will show the bug I described.
The fragment is simply this:
google_ad_client = "pub-3356683755662088";
google_ad_width = 468;
google_ad_height = 15;
google_ad_format = "468x15_0ads_al";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "3333FF";
google_color_url = "999999";
google_color_text = "000033";
Page A, that doesn't have this fragment, and therefore shows the bug, can be seen here.
Page B, which differs only by having this fragment added after the script, and which therefore works, can be seen here.
Someone tell me what's going on!!!