Just an idea, but when there are blank lines in config.php or any other phpo file that you may have hacked, that can have a similar effect -- that of disabling the html editor. But then I guess it would dissappear from both Firefox and IE. But it might be worth a search of the forums.
I have experienced a similiar problem with IE, although I haven't noticed it lately.
One way to overcome this is to use the Enlarge Editor button, which when open should have all the html editor functions. This is assumimg you can see the Enlarge Editor button on IE.
This doesn't solve the problem but it is a work around.
Yes, an idea. We had similar symptoms, and we found the domain name was the problem:
All the absolute page links were referencing www.xxx.com, and this discrepancy was upsetting IE, even though it didn't fluster Firefox. Correcting wwwroot, logging in again and clearing cache solved the problem.
I am having similar problem. The rich text editor does not seem to work in IE. Actually, it works fine, except that it is sort of hard to get the cursor move to the text area. Clicking just somewhere in text area does not move the cursor. I have to click on text already in the text area. (The "first line" also works if the text area is empty.) Tabbing works but that is not good enough solution.
Moodle 1.5.2+ (of 20.10.2005)
I found this problem now several times on different installations and computers. All the time it was the 6.00.2800 version of IE. I think there is a Microsoft problem with this version.
We found only this solution: go to the first text field and with tabs to the main entry field. Some times you will see a frame there. You can write in the frame without problems.