I found the answer in another thread for steps to disable BT. I have been attempting multiple methods to access and load whatever scanner drivers are in the most recent software listed above that I installed.
For others happening upon this thread with the same problem of "not digitally signed drivers", the problem can either be that HP has elected NOT to engage the digital signing process with MS due to time or cost, or, the drivers are in fact digitally signed after all and MS does not recognize them as such.
Rather frustrating that extensive search does not appear to speak to an effective means of either a succesful workaround or getting HP and MS to come to an effective solution to this. All I found is steps to "self sign" a file in hopes of tricking the file to install, but requiring elaborate steps with each reboot.
Also, current scanner driver shown installed is from 2006 and that the scanner is operating properly. Not the case, as I keep getting that -1500)] error above. Numerous manual Admin driver installation steps browsing through both the CD I have from the large patch/software from early 2011 AND the most recent download dated 2012 above do not list any "compatible" drivers at all, much less any that are more current than the one installed.
Current status is the printer works fine. The BT is now off as preferred. But, no scanner, which is a frequently used feature . I would be interested whether any gurus can at least steer my attention in a general direction for solution to get the scanner to work. I went through several more 'Guided Solution' in Solution Center (unplugging other USB devices, the entire turn off-unplug in certain order-reset-turn on-reconnect routines. No new outcomes.