Jens, I finally got the system to glitch again: I am starting to think the VIC is the issue, here. When the system finally glitched, the VIC chip was too hot to touch. Both the PLL chip and the FPGA were no warmer than any other time.
So honestly, I think this is mostly a case of heat buildup from the location of the VIC under the keyboard. So at this point, rather than blame this on an electrical fault with the Reloaded board, I'm thinking this is an issue caused by an overheating video chip. I don't think there's anything you can be expected to do about an overheating VIC, and I'm not using the system now anyway, since my Ultimate got here. I'll probably just end up selling off the parts so other people can resurrect their failed systems. =)
Also, your explanation about the power issue with the WiModem has convinced me that the WiModem just isn't compatible, and so I'm going to try to get an RR-Net on my Ultimate instead.
So at this point, I don't need to pursue this any further. Thank you.