Recovering from registry 51 error

For the last couple of months I have been trying to fix an old ThinkPad that failed on us. It was a low priority item but we were pretty sure we would need it fixed eventually. In an unfortunate sequence of events the battery ran down, the LCD failed, and the disk/registry got corrupted. Under most circumstances we would buy a new laptop and re-install the necessary programs. In this case we pretty sure there were some custom programs on the laptop we would need in the future. I had a backup of the data but I did not have a plan for re-installing the custom programs. Frankly none of us knew what programs we needed to save.

With the beginning of the new year I was informed that one of the custom programs that existed only on the laptop was a custom interface to QuickBooks and a SQL database. It was used in reconciling annual inventory and we needed to reconcile the inventory for tax purposes. The Boss had been thinking ahead and bought an almost identical ThinkPad laptop off of eBay. The plan was to take the old disk drive and put it in the newly acquired laptop. So I made an image copy of the drive, inserted the drive into the laptop, and then booted the laptop. Within a short period of time I was looking at a BSOD, Registry Error. So I tried to repair the installation using the XP installation disk. I surprised when it gave me a BSOD, too. Since re-installing the programs was an option we did not want to pursue at this time, I went searching for a way to repair the corrupted registry. I found this Microsoft Knowledge Base article, How to recover from a corrupted registry that prevents Windows XP from starting.

I had never seen this KB. Over the years I had almost no success going back to the last known good configuration so I was game. I followed the instructions and restored to an old system restore point. When I booted all of the installed programs worked as expected! This would have been the end to the story but after the laptop was running for awhile I started getting BSODs with a PFN_LIST_CORRUPT error message. A quick search of the Internet said this error was frequently associated to memory errors so I booted off my copy of the Ultimate Book CD for Windows and ran Memtest86. Sure enough, I got a bunch of memory error messages. I tried to swap out the memory but I kept getting memory error messages. This was not good! This laptop was bought to fix problems not replace old problems with new problems. In a strange turn of events I finally solved this problem by taking the drive out, putting it back into the old laptop, and hooking up a spare monitor to the laptop. It is not the way we wanted to run the system but it works. Hopefully we will finally migrate all of the important stuff off before we need to use it again.