Since it has been a month since my original question, I thought I would give everyone an update. I am using Proscan and the USB cable plugged into the FRONT of the 536HP. It is working fine. I have complete virtual control of the scanner. However, here is what I have learned. Don't bump the USB cable. I use the scanner desktop so this is not a problem. Don't unplug the USB cable while Proscan is running. When I first started using Proscan a month ago, without thinking, I unplugged the USB cable from the front of the scanner. I was going to use Sentinel to do some programming. Proscan froze up. When I realized what I had done, I closed Proscan. After completing the program with Sentinel, I unplugged and plugged the USB cable back in, selected "NO" and started Proscan. It would not work. I saw no display on the virtual 536HP and after a few seconds "NO RESPONSE" came up on the virtual display. Even restarting the program, Proscan would not recognize the port. So, I turned the computer off, waited a moment and started it back up. In the meantime, with the USB cable unplugged, I turned off the scanner, waited a moment and turned it back on. After the computer finished booting up Win 7 64 bit, I plugged the USB cable into the scanner (I heard the audible announcement through my speakers that Win 7 recognized the scanner. I then selected (.NO) and heard the alarm telling me the USB had been disconnected but immediately heard the audible that it had re-recognized the scanner. I started Proscan and it worked fine. A total of 2 times have I made this mistake. Repeating the sequence has solved the issue. Nutshell: Don't unplug the USB cable with Proscan running. This has been my only issue using the front USB port to virtually control my 536HP. Luckily, I did not have to buy a serial card, modem cable, or anything else.
I hope this helps.....
Alan H. - KE4AH
Haleyville, AL