Your comments

Sorry to hear about the computer, I know how painful it is to reinstall everything. Good luck to you with that.
About the settings file: please also make sure that the filename (cintanotes.db) is included in the notebook.file param (like "notebook.file = c:\my dropbox\cintanotes\cintanotes.db").
Indeed, there should be just one cintanotes.db inside of DropBox folder (but the DropBox folder may be in different places on different PCs). And no, you don't have to re-install DropBox. But you have to edit each cintanotes.settings file to point to that PC's cintanotes.db. Please tell me what "notebook.file" param value is on both your PCs? Thx
Why did it fail to sync? Did you do it like it is described here: http://cintanotes.com/cintanotes.htm#sync ?
lamatl, here are the workaround steps:

1) Find the cintanotes.db and cintanotes.settings files in
"C:\USERS\<YOURNAME>\LOCAL SETTINGS\VIRTUALSTORE\PROGRAM FILES\CINTANOTES"
Copy them to a safe location.
2) Uninstall CN using start menu entry.
3) Install CN into any folder outside of "C:\Program Files" and copy your old cintanotes.db and .settings files over into this folder.
4) Run CN
2 Tatoosh: Have you tried Alt-clicking this tag?
I see. Have you considered using software like AutoHotKey which will insert current timestamp on a hotkey in any text editor and not just CN?
Yes, this one has the priority ;) but the other way round should be possible as well.