I am not terribly familiar with Pa law but what it sounds like may have happened is that a suit was filed years ago, possibly within the SoL.I recieved papers from the van party a few years ago and wrote a document disputing this, now some few years later im I recieve a certified letter saying A certificate of readiness without being signed by all parties shall be filed with the Prothonotary 10 days from the date of this letter unless objections are sent in writing to the undersigned.
The letter you just recieved sounds strangely like a default judgement in the making probably due to your inaction regarding a suit that was filed long ago.
I would strongly suggest hiring a local atorney to determine exactly what has and is happening and apparently you need to do it very quickly.

