I agree completely that the speed of the transfer is all about the host, that's why I'm wondering if the number of hosts available has something to do with the slower speeds, plugin failure, and/or buffer freezing. Especially since it is only happening with the three viable hosts I use with Ice, 180Upload, MovReel, and VidPlay (Hugefiles just refuses to work for me). With as much traffic to as few hosts as Ice must have it would make sense that the sheer volume of data transfer could slow or overload those servers.
I don't know how hosting agreements work, but is Ice still working on linking to other hosts? I've had reliable success with Novamov, Nowvideo, Promptfile, Nosvideo, Noslocker, Realvid, TheVideo... I could continue, there are several others, but I'm sure Ice is aware of most, if not all, of them.
I like Ccleaner too. I have it installed and use it daily (have for years).