remember all those lovely back ups youy did?
find your earliest backup, save the current data directory as "current" or whatever.
copy the whole data directory into the samstockv4\samstock folder start the program.
if it starts, then something has changed within the data that samstock doesn't like
if it doesn't start then it's a licensing issue!
i'm pretty much convinced its going to be the license code. check for the obvious suich as
zeros an o'hs [is that a word?

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ones and eyes or elles etc.
as yours is the only copy i have ever experienced with windows 7, perhaps there could be an issue with the dongle driver?
Try manually reinstalling the dongle driver, it's located in the samstockv4\samstock\dongledriver directory [obviously doh!

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!!! !!! WHATEVER YOU DO, PUT YOUR UP-TO-DATE DATA DIRECTORY SOMEWHERE SAFE BEFORE MESSING ABOUT !!! !!!