Maschine freezes Reaper UI

I'm using Native Instruments Maschine as a VST plugin in Reaper. Can't say exactly when it started, but it developed a strange problem. Working with the plugin (e.g. twisting one of the knobs on the hardware) freezes Reaper UI - it becomes completely unresponsive, with meters frozen, for a noticeable amount of time (in range of 10-20 seconds); audio keeps playing though. I recently did a repair install of Windows, this theoretically could have screwed something up, but in all other ways the system appears OK. I'd rather not reinstall Windows if possible, so I'm trying to find the cause of the problem and fix it. What I've done so far: - plugged Maschine into different USB ports - verified with the DPC latency checker that there are no spikes (so I suppose it's not a bad driver problem) Using the Windows Performance Monitor, I found out that UI freezing is accompanied by a spike in CPU% (e.g. from 35% to 60%) and Page faults/sec (e.g. from 40 to 150) for reaper.exe process. Any ideas what could be causing this behaviour? Hope you Reaper and Maschine gurus can help me, at the moment I can't do anything because of it. [System: Windows XP SP2, Intel Pentium IV Quad, 4 GB RAM]

Found it! 

The setting that's causing this issue is "Save full VST state" - when it's unchecked, everything's fine. The problem is, I do want to save the plugin state! I realize that saving the full state of Maschine plugin might be a heavy operation, but why does it have effect when I'm not saving, just playing?

I will take a look at this tonight when I get home.