User Groups - Name reverts to (anonymous) upon saving

Hi,

I hope you guys can help me. I am a serious noob, and I’m not going to lie, a lot of this makes my eyes gloss over, but I sure as heck am trying.
I have STFW, and RTFM, but can’t seem to find my error.

Any time I change the name of my group, it reverts back to (anonymous). I do not understand why, and cannot find any information as to why it would do this in the documentation.

I am using the latest stable branch of revolution(2.0.4-pl2), MAMP Pro with Apache 2.0 Handler 20020903 , PHP 5.3.2, MySQL 5.1.44. PDO_MYSQL is installed. I am using FF 3.6.6 on a MBP running 10.6.4. Cache and optimizers are off.

As I said before, I am a total noob about this system. I am a designer, not a coder, but am trying to do what I can to understand this system, and this is already making my head hurt. If this is a totally stupid question, I am very sorry in advance; as this is truly disambiguation on my part, I would appreciate any help you guys could offer me. Thank you.

Are you running any browser plugins?
Any errors in core/cache/logs/error.log?
Any JS errors in the browser?

WoW
I didn’t think anyone would respond this quickly. You guys are amazing!

With regards to my plugins:
Default Plugin 2.0
Java Embedding Plugin 1.0-JEP-0.9.7.3
MoveNetworks Quantum Media Player pmnqmp 071503000004
UnityPlayer version 2.6.1f3
Facebook Plug-In 1.0.3
WebEx General Plugin Container Version 170
Contribute Plug-inInbrowser Editor Plug-in 1.0
DivX Web Player version 2.0.2.39
Silverlight Version: 4.0.50401.0
QuickTime Plug-in 7.6.6
Shockwave Flash 10.1 r53 (Side note, as a AS3 developer, I do not upgrade Flash until I’m sure it doesn’t break certain AS Functionality as it has happened in the past. I know this is out of date, but... c’est la vie.)
Google Earth Plug-in Version: 5.2
Google Talk NPAPI Plugin Version: 1.5.1.10420
Google Talk Plugin Video Accelerator Version: 0.1.43.3
Java Plug-In 2 for NPAPI Browsers 13.3.0

There is no error.log in core/cache/logs

I do get one JS error, and multiple warnings though. One in particular, that I didn’t think about checking (told you I was a noob).

Error: D is null
Source File: http://modx:8888/manager/assets/ext3/ext-all.js
Line: 7

Firebug confirms this, and says that all of the POSTS went through ok before it reaches that point.

Also, When typing, I get the following warning:
The ’charCode’ property of a keyup event should not be used. The value is meaningless.

Unfortunately, I have no clue what I’m doing here. I understand PHP, but I’m slow as hell on it, and... as for JS, even though I know AS3, I can’t seem to get JavaScript for the life of me. Strange how I’m such a noob at something I actually understand.
Thank you so much for your help and your quick response so far. I hope this is just a stupid error on my part.

-f0ru0l0rd