A final followup... after posting the code sample seen in the previous post, I went back to work on my board. And started getting the errors again!
I finally figured out what the problem was, and I bet this has something to do with the Lycos errors as well. If there are any
blank links before the <?php line, you will get the header errors. I guess that what's happening is the blank line is considered "sent" before the header information. If I had a blank line at the top of any page of php code, it generates errors. As long as the php code starts on the very first line, it appears to work.
Adding the @ in front of the header lines does not, apparently, really fix the problem. It just stops the headers from being sent. I would look at the code after it's uploaded to some of the hosts that have problems, and see if they are adding content at the top of your page. If so, that may be the problem.
I would be interested to see if anyone else can confirm / deny my findings...
This gave me the clue about how to fix my problem, which was gave similar error messages. The problem was i'd edited my lang_main.php using a web interface, and it'd put a few extra lines after the end of the file. Once I trimmed off all the whitespace things started working again.