No the problem occurs even at base clock 2Ghz for ML-37. Difference in behaviour at 2.0, 2.2, 2.4Ghz is just a timing issue being exposed. You need very rigorous testing at multiple CPU frequencies to confirm CR1 is stable.

Right now I'm trying 1x Kingston HyperX 1GB and 1x OCZ Platinum 1GB DDR400 together. CR1 may work with 2x Corsair or 2x OCZ Platinum, but I don't have those.

The IMC is very timings dependent, even stock timings might not be a good choice for a particular core revision and CR1 is even more difficult, sometimes a little ram overvolt might help a lot .

Mixing different brands with the same memory ICs may work, while same brand with different memoy ICs may not work stable at all.

In the mid-2000s, it was common knowledge that socket 754 processors needed to be overclocked with a single memory module to reduce the load on the memory controller.
The quality of the memory itself isn't the issue; the weak point in this case is the processors themselves. AMD positioned this platform as a budget platform, planning for socket 939, which was released much later, making socket 754 the default platform for the time, while remaining budget-oriented by design.