As a first-time user of Spreadsheet Compare (v. 1.35.3 on Excel 2010, Win 7), I had no problem comparing two spreadsheets on the first day. However, on the second day I encountered a problem (later resolved, see below) and attempted to get back to a pre-installation condition by uninstalling the software, deleting the SC folder (in Programs (x86)) and re-installing the software. Upon executing a comparison, SC offerred to use a previously saved session. I could not determine how to get rid of this memory of the prior installation. (The original problem turned out to be my own error by attempting to execute a comparison without assigning a spreadsheet to be compared, which resulted in "Error 9 (Subscript out of range) in procedure CompareSetup of Form frmMain".)
The settings file is located here:
C:\Users\%User%\AppData\Roaming\Spreadsheet Compare
It remains if you do an uninstall, but you can manually delete it.
Also adding note to the help file.