I've seen the threads about migrating to a new computer. And, I understand why those require a reinstall. But, simply upgrading a hard drive with a byte for byte clone should not require this, should it?

Every other application (gaming rig with 100s of games installed) all run fine. But, RF throws a 21051 unknown product code.

The ONLY thing I can think that would be different between the two pieces of hardware are the serial number and maybe the volume ID.

Any chance a serial spoofer using the old drive's serial # might work?

only reason I'm hesitant to do a reinstall is this machine doesn't have an optical drive. IIRC installing over the network took ages, and creating an iso on a flash drive is nearly as big a hassle--plus I only have v7. So, after all that I still need to upgrade to 7.5. Seems an awful big runaround for something that should take 30 seconds to overcome.