I know you've reported that you lose the manual vs. auto setting when you update your profile, and I've looked carefully over the code to see if I can figure out why it's happening and I haven't been able to find a cause.
This is IE8.0.6001.18702IS, XP pro 32-bit service pack 3, running on a corporate network. Plugins are Adobe shockwave flash, adobe PDF link helper, Java. There is the usual overzealous corporate security stuff to lock down the machines.
Yeah, if the page doesn't load completely that could absolutely do it. Also, if you have trouble resolving the domains of the some of the helper scripts, that could also do it. So if your browser is having trouble reaching either of these files that load in the background:
Another thing to try: before you enter your new car description, click the "change type" link at the top of the page next to "Current Type: [car model]".
Take a look at the settings there and make sure they're all filled in. If they're not, do a hard refresh of the page. In IE8 that's Ctrl + Refresh. Check the model with "change type" again, make sure it's all there, write your new description, save.
Weird behaviour this evening. Edited it a couple of times, OK, went back to the car page via the home-page-banner, the trans/fuel/engine details were missing. Edit car/edit type, make/model/year were OK, but the transmission/fuel/engine options were greyed out (+ could not be selected).
Cancelled out without saving, went back to the car page, still bad, went back to the car page again without saving, it was ok.
Edited ... the make/model/year/engine/transmission were OK, but the fuel type entry was greyed out. Went back to the car page without saving ... everything was OK again.
The same with repeatedly hard-refreshing (ctrl-R) when on the edit screen. It's good most of the time, but perhaps one time in 4 or 5, some of the edits are greyed out (sometimes just one, sometimes the 3 bodystyle/engine/fuel/transmission).