I had a Tax Lien which was incorrectly placed when the XXXX sent tax payment money to the IRS as I had paid two years taxes ( a XXXX and a XXXX ) with the same check. They processed the XXXX return and then found they were short the money they sent to the IRS - go figure. 
I have had the tax lien released XX/XX/XXXX and notified Experian in both XX/XX/XXXX and XX/XX/XXXX. It is still on my credit report. Again, the credit dispute process is a joke. There are no penalties for the credit bureau putting erroneous information nor in simply ignoring disputes made through their website or by mail.