Bernard,
If you upgrade TheSky to TheSky64 you will need to replace the Bisque ASCOM 2X Mount Adaptor with the latest version too.
The latest TheSky 10.5.x installer actually installs both versions of TheSky on your computer, the 32bit version and the 64bit version and you can choose which one to launch on demand.
If you want to swap between TheSky versions and control them by the automation interface you need to launch the chosen version one-time-only “As Administrator” wait a minute or two then close it down again and restart the same version again normally, after that your external control software will interface with that version of TheSky correctly. If you want to swap to using the other bit version of TheSky you need to repeat the same process.
The latest Bisque ASCOM 2X Mount Adaptor setup page has an extra bullet-point selection to choose which bit version of TheSky that you want it to work with and you need to configure that in both ACP’s Telescope setup and in MaxIm’s guider Guide Via setup as you did yesterday.
IMO TheSky64 is still a work in progress as far as third party hardware drivers are concerned and it is currently a bit of a lottery whether you will find 64 bit drivers that will work with the TheSky64 and your existing hardware, having that problem myself with my Pulsar dome driver (although I have found a work-around using the ASCOM Device Hub as a go-between).
If you use third party applications with your Paramount such as PemPro and CCD Inspector I find these quite difficult to work with TheSky64 and when I need to carry out a new Pec adjustment or collimation adjustment I usually fall back to TheSky32 for those tools and go back to TheSky64 when finished.
The only valid reason right now to swap to TheSky64 is if you have one of the latest APS-C or Full-Frame mega pixel CMOS cameras which create such large image files that cause TheSky32 to freeze or crash, such as when creating a T-Point model for instance, because the memory limit for 32bit applications is reached, and that has nothing to do with the amount of physical RAM memory you have on the computer, a 32bit application can only access a small proportion of that RAM while a 64bit application can access all of the physical RAM available except for the part used by Windows and the motherboard itself.
The latest 10.5.x build of TheSky32 does have ~six years worth of bug fixes over your 10.3.x version and it is worth upgrading to the dual 32/64 version of TheSky for those fixes and apart from a few unintentional bugs that were introduced along the way, and quickly fixed, the latest TheSky32 does work well with my eleven year old Paramount MX when I need it but I do have to bin the camera at least 2x2 or even 3x3 to avoid hitting that memory limit.
I don’t know whether TheSky64 is compatible with Windows 7, according to the requirements page TheSky Pro is currently only listed as compatible with Windows OS's 10/11, you would need to check with Software Bisque sales to be certain.
There are a few user settings that you have configured in your copy of TheSky32 that do not migrate across to TheSky64 10.5.x when you update from 10.3.x, although the settings do migrate ok to TheSky 10.5.x 32bit, but those are relatively few and documented on the start-up splash screen when you launch TheSky64 for the first time.
Having both bit versions of TheSky loaded actually takes some of the stress out of updating as you can dip in and out of both versions as time allows.
If you don't have one of the memory hungry CMOS cameras you can continue using TheSky32 with ACP and experiment with TheSky64 alongside then configure ACP and MaxIm to use TheSky64 when you are happy that your existing hardware drivers are all compatible and working reliably.
HTH.
William.