haha, ya. "It works for me". Yay, thanks for wasting your 10secs of time that did nothing positive for the universe, haha.
I can't say I know what the problem is, but it seems you are someone that can get around a bit in troubleshooting. This is what I personally would do..
First, I would disable all of the other plugins one at a time and see what happens. I'd get it down to the 2 that you assume are the challenge. Enable one, disable the other...and vice versa. I'd get it down to an elimination process.. Once you know, with 100000% certainty that it is indeed down to those 2 plugins creating the conflict (and you do not experience the issues with editing at any other time), then you have narrowed it down to step 1.
But see, your original type up shows in 1) that you have other editing page problems. Then, in 2).. you are showing more editing page problems and butting it up to the plug-ins. I'm going to suspect that it is not the plugins if you are experiencing other editing page problems w/o the plugins.
So, if what you typed up is indeed the case, there is something else wrong that is impacting the editing page already... maybe when you enable the plugin, it just makes it worse? What I can see, the problem is elsewhere.
I would also see if the issue can be duplicated in other browsers. Maybe you have some add-ons added that are conflicting w/ WP. I'd try WP in both IE, FF, and maybe even Chrome.. and see if it continues. If not, you have narrowed it down further..
Try it on a different computer...see what it does. Keep going if that isn't it..
Personally, after doing google searching around about the editing page problem in WP (minus the blame on the plugin), if I could not find someone that was experiencing it too.. I would suspect somethiing on my end. If it wasn't the computer, browser...I would suspect server side. So, I would probably back up the blog... then wipe it out and reinstall everything.
Oh, yes..I would update to php5. See, from everything you are saying, it is obvious you are experiencing other challenges. You can't do auto WP updates cuz it just hangs on unpacking? Mine will go to an unpacking page, but at the bottom..it will eventually say done. Sometimes it takes a bit. By hitting back and not letting it finish, you could be screwing up the installs?
Idk...from what I'm reading, there seems to be a challenge elsewhere than the plugin. The plugin is just contributing to it and making it worse. I'd wipe it all off the server and get a fresh install done if php5, 3.04, browswer, computer, and other elimination processes don't work.