When you create
a new web part page in SharePoint, its left navigation column becomes empty.
Reason for this is that the left side navigation is defined in the Master Page
content place holder and templates for Web Part Pages shipped with SharePoint
override this content place holder and delete its content, thus displaying
empty left navigation.
for this is to change the page so it will not override the menu place holder,
but inherit it from the Master Page. The place holders we are interested in
1. There is this tag which needs to be deleted or commented (this one hides the
2. Delete only this tag as this is what
overrides the default nav coming from the master page.
3. Leave this tag as it is,
if this is deleted(as said in other posts) it leaves a blank row on top the
left nav which is not what you would want.
4. Save the file.
You will get a warning saying
you are about to customize the page. Just go ahead and open that web part
again. It should have that good left navigation.