As always, I am coming at this from a support perspective, and I know that userdoc doesn't exist just to be useful for support. :) But we see a lot of people who, when we say "It's bad HTML, go see this FAQ", come back with "I tried enabling image placeholders and it didn't work". I think, also, there are a lot of cases where there's an entry with bad HTML that's hard to find, because the user looks at the "it's bad HTML" bit, and looks at thei friends page, and thinks that the top entry that's displayed is the one that's causing the problem. (It's not.)
So, it might be worth reorganizing it to make it clearer that the causes, and solutions, for horizontal scrolling problems, and the causes, and solutions, for weird entry order, are not the same.
There are two main problems that can cause your journal or Friends page to display incorrectly. First, you or someone on your Friends list may have posted content that causes your journal or Friends page to appear wider than your browser window, so that you need to scroll sideways when reading the page. Second, you or someone on your friends list may have posted content that causes your journal or Friends page to display out of order, with old entries at the top of the page, and newer entries below them.
Horizontal scrolling occurs when something in one of the entries is wider than your browser window. This can be caused by large images, long strings of text without spaces, a poll with a large text entry box, an HTML table with a fixed width, or HTML instructing the browser not to wrap a pargraph onto a new line.
To avoid these issues:
* Use the <lj-cut> tag when posting large images or other wide content
* Occasionally enter a space in any long strings of text
* Shorten long text
* Use HTML link tags instead of just pasting in a long URL
* Limit the size of any picture posted in an entry
* Limit your poll's text entry boxes to a smaller size. You will still be able to enter the same amount of text in a smaller box; the amount of text entered is controlled by the "maxlength" property of the text box, which can be up to 255 characters.
If the problem is caused by a large image, you can turn on placeholders for images posted in your friends' entries by selecting the "Use image placeholders on your friends page" option on the Edit Personal Information page (http://www.livejournal.com/editinfo.bml). This will cause all images, or all large images (depending on your chosen setting) on your Friends page to be replaced by a small generic placeholder image, which you can click on to view the posted image. (Images that do not have a defined size will be treated as large images, for the purpose of a placeholder.)
It is also possible for horizontal scrolling to be caused by incorrect overrides in the S1 style system. If you have overrides in place that involve the width of your journal, you may want to make sure you are using the correct overrides for your style, and that the width of the journal plus the left and right margins do not exceed 100%.
ENTRIES DISPLAYING OUT OF ORDER
Entries can display out of order if an entry on the page contains HTML that is incorrectly written. A quiz or other external content that is pasted into a journal entry is the most common cause of this problem. This frequently affects journal layout severely, and may cause other entries (especially those that follow the entry containing incorrect HTML) to display in the wrong place, such as at the top of the page, or not to display at all.
To avoid these issues:
* Use the <lj-cut> tag when posting quizzes or HTML tables
* Ensure that all opening tags (especially table tags) have a corresponding closing tag
* Ensure that closing tags (especially table tags) occur in the correct order
The entries that appear at the top of the page are not the ones that are causing the problem. However, there are ways of finding the problem entry.
If there is a comment link at the top of the page that does not seem to be attached to an entry, or a comment link with a current mood, these belong to the problem entry. Clicking on the comment link will take you to the "Read Comments" page of the entry that is causing the problem.
You can also determine the problem entry based on which entry appears at the top of the page. The entry at the top of the page is almost always the entry immediately following the problem entry. Make a note of which entry this is, and then disable HTML in your journal or Friends page by appending ?nohtml=1 to the end of the URL, or &nohtml=1, if there is already a ? in the URL. (For example, you can view your Friends page without HTML by going to http://www.livejournal.com/users/exampleusername/friends?nohtml=1) Find the entry that had been at the top of the page; the entry immediately above this one is most likely the entry that is causing the problem.
FIXING THE PROBLEM
If the entry is yours, you can edit it yourself to add an <lj-cut> tag, correct any HTML problems, or remove the problem content. If the entry is not yours, you can ask the person who posted it to edit the entry.
Another option is to create a custom Friends group named "Default View", placing everyone in that view but the person who has posted the entry. This will temporarily remove the friend from your Friends page, but not from your actual Friends list. After some time, you can remove the Friends group, as the post causing the problem will no longer be displayed. You can also temporarily remove the friend from your list, although this means that the friend would not be able to see any protected entries that you write.
You can also simply wait for the post to scroll off your Friends page. When there are enough entries on your Friends page, the problem entry will be pushed back to a previous page, and will no longer affect your main Friends page.
How do I use an lj-cut? What are the other LiveJournal-specific tags?
How do I edit or delete a journal entry I wrote?
What are custom friends groups? How do I use them?
Why do my overrides not work blah blah blah?
whichever FAQ that is