Well I did a little troubleshooting this AM. As a reference I am running firmware ver. 1.02.03 in my BCD536HP. I connect the scanner to my computer and went into the serial mode. I didn't run any program to access the scanner. I let it run this way for about 1 hour. No problems were seen. I then started ARC536 beta ver. 0.89 build 10. within about 10 minutes of running VC and nothing else running on the computer it went into Mass Storage Mode.
I also checked in Device Manager and confirmed that the computer saw the scanner in the serial mode.
UPMan I don't know if this info will help but I thought I would pass it along. I know with firmware ver. 1.03.03 the scanner will go from serial mode into Mass Storage Mode also.
I am staying with firmware ver. 1.02.03 since I found that ver. 1.03.03 makes reception of my local fire department,
http://www.radioreference.com/apps/db/?sid=6739,P25 Phase II reliable only about 85 - 90 % of the time. At least with 1.02.03 my reception about 99% reliable with the mode set to FM and only receiving the closest site frequencies programed.
This makes me think that maybe the problem could be with the serial driver or with the software used to access the scanner rather than the scanner itself. Is the serial driver 64 bit or 32 bit. I had a problem with a 32 bit deriver on my computer, new Dell XPS and Windows 7 Home and Office, not working. I finally found the 64 bit driver and the device works great now.