Sorry to bump, but still having problems. Related threads just don't seem to apply to my system.
The problem:
Still cannot perform manual incremental PC Image backup to USB Ext HDD from my new Windows 7 Ultimate (64) desktop.
Original, initial Files/folders and PC Image backups to Iomega USB Ext HDD went fine, as did creation of a system repair disc shortly after setting up the system from Dell.
Subsequent
Files/folders backups and
copy/paste of files are also fine.
I do not leave my Ext HDD connected, so I run manual backups weekly.
I always shut down Carbonite and MBAM Pro 1.44 active protection module before I plug in the USB drive.
When I try to do the incremental PC Image backup, the backup utility either doesn't start or starts and runs most of the way, and then (in either case) hangs, and also freezes out Windows.
No BSOD, no error message, no stop code. Just hangs (backup and restore "not responding"; mouse moves cursor, but cannot execute anything to open task manager, shut down, etc.). Have to hard boot.

Troubleshooting:
System is fully patched and clean; periodic smart defrag and CCleaner removal of temp files, etc. It is stable, aside from this issue.
Neither KB 976972 or 977074 (mentioned in similar threads) applies to my system.
I also tried the workaround that used to work on my Vista Ult SP2 32-bit system, which was to to "schedule" the backup and then click "backup now".
No joy.
The destination Ext HDD itself is fine (it is new and has plenty of space and it takes the files/folders backup just fine).
I ran a complete, extended hardware diagnostics last week (20 hours worth!) and it was all fine, so another chkdsk wouldn't help. Moreover, the source C: drive is new, huge (1.5 TB) and mostly empty. IOW, there aren't that may sectors in use.
I don't have an internal hard drive to use for backups, unfortunately.
I KNOW from all the discussions that there is something
really "off" with Windows 7 backup, esp 64-bit, but it is very frustrating and I don't know how to fix it.
(Never had these issues on previous XP 32 or Vista 32 or even Windows 7 32 systems.)
QUESTIONS:
Am I doing something wrong?
Is there some way to successfully create an incremental (or a
new?) PC Image by configuring the settings for "manual" vs. "scheduled", and/or including the PC Image or "computer" backup with the
files backup vs. doing it separately, etc???
I see several 3rd-party backup apps mentioned (Paragon, SyncBack, Acronis), but none seems entirely problem-free, either.
(I am afraid to delete the one PC Image backup I *do* have from the Ext HDD, in order to try again from scratch.)
PLEASE PLEASE advise as to how to proceed and Thanks very much in advance for your assistance, as you can see that I am completely over my old head with this,
MM