Usually when Firefox gets the shakes it's because you don't have a bookmark at the top of the tree structure. I found the easiest way to overcome this was to open the bookmarks in the sidebar and ensure the main b/m folder is situated correctly at the top, with at least one bookmark in that folder. As you have said you've lost your bookmarks, that could very well be the cause of it.andrew91 said:
Lost bookmarks, where have I seen that before?!! Your bookmarks are situated (for windows) Documents and Settings >> *User Name* >> Application Data >> Mozilla >> Firefox >> Profiles >> *User Profile* >> bookmarks.html. If you haven't created another profile, your default profile will be listed as XXXXXXXX.default(user) where XXXetc is a random string of eight letters and/or numbers. If you find the bookmarks file you shouldn't really be having any problems. You could always try a system search for bookmarks.html - remember if you have more than one profile to check the path when found. The bookmark file can be copied from profile to profile but more info as and when you need it.
Let us know how you get on andrew91.