Html Editor Error

I don't know if any of you have come across this problem but i'd appreciate some help in rendering the situation. If i add an unordered list into the window it works well

<ul>
<li>user</li>
<li>pass</li>
</ul>

But when i edit it it comes out as so:

<ul>
<li>user
<li>pass</li>
</ul>

The only the last li tag is closed the est are left open and to be able to render the html "xhtml 1.1 transitional" properly it fails.

Is there some regexp that has been written to fix this?