In my case it turns out to be the fault of 2 sceneries called Pulkovo Approaches and Project ULLL. I'm not sure which of these is the culprit, I believe Project ULLL contains scenery for 38 or so airfields in the St. Petersberg area of Russia and I can only think that there is some nav data in amongst that scenery that is causing the issue with the FS9 GPS because if I disable those sceneries and re-start FS9, the problem is gone.
I have tried re-naming any files that I find in the 2 scenery directories that have Nav Data in their name, but that doesn't make a difference.
Bottom line for me, with Pulkovo Approaches and Project ULLL installed, LV issue on my GPS, without those sceneries, no LV issue.
Hope this helps