I don't use IE, but too many people do use it, and so I am forced to test all sites I work in it too.
Besides other problems (commonly found in IE), the jQuery 1.5.0 is generating a object issue that affects the entire OxWall site (including the Ajax Login and most forms).
To fix it simply change the jQuery file 1.5.0 by any other (newer) version of jQuery. I'd suggest the version 1.6.1 from http://code.jquery.com/jquery-1.6.1.min.js. Download it from web and then upload it in your OxWall site at /ow_static/plugins/base/js.
As I am absolute new to OxWall, I rather not play with the source code yet (even being a savvy web programmer). I believe the developers can push an update to fix this issue as soon as they read this post (and, to be more than honest, I am curious to find out how long will they take to read this post, or even if they WILL read it). ;)
Meanwhile, a quick "trick" can allow for anyone to easily fix this issue without any code modification: simply rename the jquery-1.5.0.min.js file to jquery-1.5.0.min.bad.js and then rename the file jquery-1.6.1.min.js to jquery-1.5.0.min.js. This way, without any extra modifications, the site will load the jQuery file with actually is the 1.6.1 version regardless of its name.
Hopefully, an update for this issue is on the way (maybe the OxWall version 1.2 will have it corrected?).
P.S.: I saw another thread (topic: http://www.oxwall.org/forum/topic/1016) about the same issue, and people over there claim that jQuery 1.6.1 may result in issues with some plugins. However, I've extensively tested it and I didn't identify any issue. Please, help me if you can testing it on your own installation and reporting any found problems here.