You've had some amazing responses to your question and I do agree, the first thing you may want to do is locate (if you can) your closing packet from where you bought house. If you are not able to find, locate your realtor (If he/she is still in the business) to ask if they still have a copy or can identify which closing attorney closed your loan. In Columbia SC, most closing attorney's have direct ties to the title insurance company.
Your closing attorney along with the title insurance company will be able to determine what the problem is.
I am assuming that the cloud on your title was uncovered by the "now" closing attorney. It would help your situation if you knew what the cloud on your title was and could communicate the issue to the "then" attorney and title insurance company.
Along with all the other wonderful answers, I hope this helps!!!
Regret the problem.
Since you have title insurance you are fine provided it is a prior lien.
If the title has been clouded due to issues created by you, then you pay.
You should be fine.
If the title issue is covered (insured), then contact the title company. If it's not a covered issue, then it'll be on your nickel to resolve it. Unfortunately, there are often plenty of exceptions to coverage.
Review your title policy thoroughly.
I'm assuming that you're suggesting that the title was clouded when you purchased 4 years ago. In that case, you should be protected.
Remember, though, that there may have been clear title when you bought but something may have occurred during the period you've owned the property. For example: An unpaid repairperson filing a lien. Or an unpaid water bill--that can also result in a lien on the property. Or if you had something like windows installed, you may have signed a document securing the financing on the home improvement with a lien on your property. Or unpaid taxes. Or a lawsuit. In those cases, title insurance won't help. It can't protect against liens that hadn't been filed at the time you got the insurance.
Hope that helps.