OK, thanks to harpo, I've been able to deduce that there is no error when trying to run my program on XP. There's obviously something wrong with my test machine, but I'll get that sorted later.
As far as I can see, v1.2 is done. The only reason I'm NOT putting the download up right now is as follows:
I plan to switch my hosting provider this weekend; during the transition as I get the nameservers adjusted, my server will be down. Obviously, I don't want such downtime to interfere with the release of this program, so I will be waiting until AFTER the switch is complete. I plan to start Saturday morning or maybe even Friday night, so depending on how long it all takes, the tool could be out as early as Saturday afternoon, but also might not be until Sunday or Monday.
So, Sins Data Converter v1.2 coming this weekend! I will put up a full list of changes when the time comes, but the two biggest new features are drag-and-drop, and full subfolder support.