I think some one mentioned memory problem here as well. I just had a problem. Had Dynamic HTML Editor open with 2 pages on the go, and PSP (Paint Shop Pro 7) with a few pics on, then, found in Dynamic HTML Editor the F4 and Del buttons wouldnt work (could do it through the menu though). Then when I FTP my page to the site, and opened IE to look , and closed and opened Dynamic HTML Editor (or rather tried to open Dynamic HTML Editor as it wouldnt..!) I had been doing a bit of graphics work so I guess that its my computer not your great prog. Just for info..
I would also like a go at the beta if poss as am having lot of fun with Dynamic HTML Editor at the moment.