I'd got CSR Hall at last summer group buy and haven't used it much until recently. I discovered it's a great plugin, but I noticed I have an annoying problem with it -- for some reason it doesn't save High Freq parameter and when i reload a project it sets to default (8.2 kHz) which is too high for me most times. I can write automation line and it works as a workaround, but it's a bit disturbing workflow and I already use a ton of automation, so the screen is messy.
The DAW is Reaper.

add an eq?

Maybe the Plug-In Preferences are corrupted. Try trashing those, on a Mac that usually solves such problems.

That would help when I use it as send effect, but I often put it on insert.

It's a CSR problem - worth reporting to IKMM. Hi Freq is not saved in .fxp files either. Seems like that parameter is not exported anywhere.

Meanwhile, in Reaper, add an Automation Envelope for high Frequency, and use Trim/Read to set it to the desired frequency, then switch the Envelope to Read. Here's a project I reloaded earlier, with a 4.1KhZ setting:



Big pic: http://img138.imageshack.us/img138/1425/dsr352csrhall.png

Check your modulation window. Maybe it has added some modulation control so it is keep coming back to that...

Please open a support ticket - this is the best way to get bugs verified and subsequently fixed. Thanks!