I'm having the same issue on a fresh install of 2.3.6. Clicked on the Stream button and then BAM, the recording is gone. It's deleted from NPVR and deleted from the recordings folder. One thing that might be a clue is that I had been logged in to the "Config" screen via EWA to change the channel icon setting. Clicked Submit, then clicked TV Guide, then clicked Manage Recordings and then the Stream button for a show. Could still having admin privs cached in Firefox have something to do with this? I also have the Ghostery plugin installed. I can see where that might break functionality but I don't think it should cause recordings to be deleted. The log did a rollover, so it isn't much help right now. I'm recording some "throwaway" shows to test with and will post a log file soon. I did glance at the log (web.log, correct?) and saw no reference to the recording that I clicked on.
Athlon 64 3400+, 2GB RAM, Win7 x64 Pro, Hauppauge PVR-150, PVR-500, NPVR 2.5.9, 4 MVP's and a partridge in a pear tree...
On a clear disk, you can seek forever...