If, like me, you are running caustic or the Caustic Modular Prototype Synth in Windows 7 (and some other versions of Windows), you may find that you save a preset - and it seems to work - but can't find it when you try to return to it on another occasion. This depends on whether you are logged in as Administrator, a user with Administrator-level privileges, and where you installed the software....
The problem is that Windows applies user rights automatically, behind the scenes, and inconsistently - you may not have user rights to modify the contents of a directory of something you installed yourself!
1) Right click the program directory, go to 'Attributes', and remove the 'Read Only' attribute; click apply, and answer the dialog to apply to files AND subdirectories; right click, then go to 'Properties', select the 'Security' tab, and give yourself and any other users you want to be able to write data, 'Full Rights' in the dialog box (upper half)
2) Go to the user data directory (for Caustic) under C:\Users\<Username>\My Documents\Caustic, and repeat the above actions.
I have found that this problem occurs inconsistently - it happened on my main (AV server) PC, but not on my Netbook, both running Windows 7, and installing to the same named and placed directory - and the problem did not occur on my old XP laptop or tablet PCs!
If you have this problem with other programs, or with VST plugins that store data in a directory, the same procedure usually fixes the problem.