Cannot install trial PE7

Question

System is ECS RS400A, 3ghz P4, 2gb, 500gb/250gb/160gb drives, Nvidia 8400GS, XP Pro SP2. Runs PE2-3-4 like a rock, XP is in good shape, no other "wierd Windows" issues going on, other installs proceed just fine. Son purchased new Samsung flash mem camcorder, and he's used to PE4, in fact more used to it than I am (!) and so naturally wants to stay with it. New cam outputs only MP4 so now we must do "something else" for software, as PE4 wants nothing to do with MP4.
Downloaded and installed trial version code. Ran the small unzipper which correctly unzipped files. Was able to install this code onto a different machine in our network, over the network, without issue. Now trying to install on the downloading machine, and it fails.
Starting at setup.exe, the installer window comes up, I select "english", then proceed, and then after 2 seconds an error dialog box entitled "windows installer version blah blah.." comes up, listing all the various switches available to windows installer, as if the command to installer was wrong.  It exits.
I saw and ran the KB which evidently updates windows installer, but it made no difference.
So, I get the dialog box with the installer switches listed, then it exits and that's all, folks.  Have to confess, have never seen this one before.
I must say, so far I'm not particularly impressed with 7; either on son's 3ghz P4 Asus @2gb, nor my ECS which currently refuses to install. On the Asus, it spends most of its time doing "something" which pegs CPU at 100% for extended periods of time, and performance is quite jumpy and fairly unlikeable overall. But my mission right now is to try it on my ECS to see if it is equally bad there or if it actually works. Or, maybe we have to move on to some other software with MP4 support... thought we've been so happy with PE in the past I hate to leave now.
Are people actually using PE7 successfully?  Don't want to sound "negative" but every so often, things are released that are just useless... so if this is one of them I'd like to cut and run now rather than screw around forever trying to fix everything with patches, reinstalls, mods, etc. etc.  Been there, done that, it's all overrated.
Thanks for your input.

Answer 1

Ok, I set up a spare disk, installed a quick XP pro to test, installed all the proper drivers, and then installed PE7 again.
This confirmed my earlier problem: upon loading the MP4 clips (total of 3 test clips, 4 minutes total length), the system goes into some sort of huge 100% CPU operation which lasts for A Long Time... it works and works, and slowly the yellow line proceeds through the clips... so after waiting maybe 15 minutes, it appears to be done with that (lots of time for a 4 minute clip), then I tried playing the clips.  Performance is pretty much useless again.  Bear in mind now that we have installed the trial here on 2 completely different machines, each running p4 @3ghz, each 2gb memory, one is an ECS motherboard, one an Asus, and both these system have pretty much flawlessly run everything else we throw at them.  And they both run PE4 quite happily as well, albeit not with MP4 files.
But now they both go into some kind of apoplectic seizure with PE7 attempting to work with the MP4 files we send to it.
This started because we gave our son a new Samsung camera which outputs MP4 files.  Any chance there might be something "wrong" with the MP4 files this things puts out?  Maybe PE7 just isn't happy with them?
Our experience with PE4 and prior was that one could just blithely drag the 'pointer' back and forth in the timeline and the preview window would display frame for frame, wherever you were.  As soon as we try that now, CPU instantly hits 100% and it's dead in the water again until we wait and wait and wait.  It almost feels like there is some sort of perpetual "conversion" going on, frame for frame or something like that.  Very unnerving... unusable, actually.  I'm very intrigued to hear how others are doing with MP4 stuff.
Something is clearly wrong but I have no idea what it might be.  I would think this should have come up before though...
Clues very much appreciated.
Thanks,