I had a strange issue with IE6 recently where there appeared to be a random character that was displayed when the page was rendered:

It became apparent that it was actually the last letter from the above select element but it only happend in IE6 and not IE7 or Firefox.
The select element and the button are both floated, have % widths and are in a containing div which has an absolute width set in pixels. After much searching I found this article and I was able to fix it by using the following style on the button:
margin-left: -10px;
and the page then rendered correctly:

Don’t you just love IE6 bugs?!