I am also experiencing this problem. Like Josie Kirker (8:58am Jul 5, 07 PST (#59 of 93)) I purchased my copy of CS3 through Tech Soup (a San Francisco-based administrator of software donation programs by major corps, like Adobe, to small-to-medium nonprofit organizations). What I received appears to be the retail package, BTW, not a volume-license package: it came in a box, with three CD's in a plastic CD case (including one of video demos), and a small "workflow guide" manual that fits in the box.
I'm running WinXP Pro-SP2 on a P4 Inspiron 8200 with 1 gig of RAM. Also running Webroot Spysweeper, Zone Alarm, and Norton AV 2006, and am also running into this problem.
I no longer recall the exact sequence of install/update I first used but I do recall I had to turn off Spysweeper to install at all, and Acrobat only installed successfully the second time I reinstalled it. (The other programs in CS3 didn't have this problem.) I activated CS3 from within Illustrator (the first program I opened), and everything except Acrobat works as I would expect it to.
Before opening any programs, I looked for updates. Several updates did not install the first time I downloaded them (I wasn't keeping notes on this yet so I can't say which ones, sorry), so I rebooted and ran updates again. After several iterations I got a message box saying that I needed to re-install Acrobat, Extend Script Toolkit, and Adobe Color Common STI Update. I got out the CD and re-installed Acrobat (the only one of those three on the CD), and was told that the installation was successful.
But when I tried to open Acrobat I got the "memory could not be written" error message, found this forum on Google, and realized I should have kept notes.
Currently Acrobat will run for 15-30 seconds, then gets the "serious error" message and closes; a few moments later, after the program has closed, Windows posts the "memory cannot be 'written'" error box. While Acrobat is running, both "Activate" and "Unactivate" are greyed out. Also, if I select "About Acrobat" while it's still running, the program doesn't crash until after I close the information box.
I'm no techie, but I've been using computers for over 20 years and can follow instructions, am not fazed by DOS command lines, and if necessary (and told exactly what to do) can edit a registry line if that's how to fix this thing.
Jeff-from-Adobe, how are you doing with discovering what causes this problem? Is there a specific procedure I can perform that would give you information you need to diagnose it? I'm not willing to take shots in the dark, but I'm willing to try a few directed experiments and report back, if you tell me what to do and what to look for.