HP OfficeJet AIO - Scanner Twain Drivers Do Not Work

I'm working on 7100RC 64-bit. I have a HP Officejet 4215 All-In-One. I installed the full HP software downloaded from the HP web site for Vista 64-bit for this AIO. It appears to install OK, but the scanner does not work from the HP Solution Center (Digital Imaging Monitor) software which use the TWAIN drivers (I think). I can however, access and use the scanner by using another application - Adobe Acrobat, for example - by choosing to use the WIA drivers. (If I choose the TWAIN drivers to scan in Acrobat, the operation dies.) Using WIA from another application is a workaround, but I would prefer to use the HP Solution Center because it gives me a lot more flexibility and options. I have uninstalled and reinstalled a couple times with the same results.