How can tinyURL help you ?? Please explain !! What are those links ?? please explain. I don't think links can give you negative value, at most they will give you 0 value. If that was not the case competitors will be putting links to bad neighborhoods to lower one another's PageRank. A link can never carry a negative value (reason explained above) at worst it will give 0 value. Don't worry about your signature links. Do worry about having lost any good PR link pointing to your site. But MORE IMPORTANTLY worry about selling/putting unrelated links on your pages google can easily spot them and lower your pagerank (I have had experience with putting unrelated links on my site and getting a lower PR in return) For example if you site is about travel and google finds a link to a mortgage institution on your pages then google might think you are selling links and lower your PR (well that is just the way I SEE IT)
just continue working on the site.. and u will get your PR back.. my site was on the situation and now is with the PR3 back..
You must check your backlinks especially if you done in LE. Check those sites that sometimes they remove you for their own benefit only.. You must check you reciprocal links every now and then. And by the way you must not stop in building backlinks since it is the reason for PR (quality backlinks).