Nuvi 750 - Can't Unlock Maps

Hello all.

I've been generating my own custom maps for about 10 years now but after the April 6th rollover I can't get any of my Nuvi units I've been using for the same amount of time to accept the maps I make. I keep getting the message "Can't Unlock Maps" when the device is running it's initial boot sequence. I know it has something to do with the way it tells time and date from the satellites it's connected to.

Here's how I generate my maps:

1. I use ArcMap 9.3 to manipulate data that I collect with a Spectra GPS recording device.
2. I then well export the layers I want to use in my map into their own .shp files.
3. I import these shape files into GPSMapEdit 10.0 and create an .mp file with my collected data.
4. I then use a key generator and Sendmap 20 to create an .img file that I can lock to only the serial numbers of the GPS units at my disposal.
5. After I create this .img file I compile it using a program called cGPSMapper to create the final product to use with my Garmin units.

Until recently everything worked just fine. I have tried a few other forums trying to find anyone who has had similar issues or maybe someone who has had issues of the same type with a different format GPS device. I want to know what I can do short of taking out the expiration date and completely unlocking the maps to protect my data. It's a hobby of mine and I have recorded a lot of stuff. I just don't want someone to be able to steal one of the units from my truck, boat or ATV and be able to just have the data I've spent a lot of time and effort collecting and learning how to use properly.

Thanks in advance for your time.