Hi Biggestted:
Sorry, I still haven't found a solution. I contacted Apple Support by phone and was put on hold five times before the service rep told me that the DEP error I was describing is caused by a virus and has nothing to do with iTunes. I've done full system scans with Norton Internet Security and Malwarebytes Anti-Malware and both scans were clean, so unless I have some hidden rootkit on my system, that suggestion by Apple seems highly unlikely. I suspect the service rep I was talking to at Apple didn't understand that the error occurs when I close my iTunes GUI, and not when I shut down Windows.
I've tried multiple suggestions in other threads related to DEP errors with iTunes v. 11.2.x but nothing has worked so far. I've noticed that most Vista users in this thread see their DEP error when we try to close iTunes, while 64-bit Win7 and Win8 users in other threads that were able to fix their problem had an issue opening iTunes or trying to connect to the iTunes store. I wouldn't be surprised if the root cause of the DEP errors on Vista systems is unique to our OS.
Other users that have downgraded from iTunes 11.2.x to iTunes 11.1.x, have reported that they get an error stating "The file iTunes Library.itl cannot be read because it was created by a newer version of iTunes." If you decide to downgrade, turingtest2 has posted instructions here on how to restore a previous iTunes library.
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MS Windows 32-bit Vista Home Premium SP2 * Firefox 29.0.1 * IE 9.0 * 32-bit iTunes v. 11.2.2.3
HP Pavilion dv6835ca, Intel Core2Duo CPU T5550 @ 1.83 GHz, 3.0 GB RAM, NVIDIA GeForce 8400M GS