Opened Reaper, Selected "Virtual Instrument on track" (REFX Nexus) and get this :
Process: REAPER [581]
Path: /Applications/REAPER.app/Contents/MacOS/REAPER
Identifier: com.cockos.reaper
Version: ??? (4.11)
Code Type: X86 (Native)
Parent Process: launchd [290]
Date/Time: 2012-02-03 15:12:23.471 +0000
OS Version: Mac OS X 10.7.2 (11C74)
Report Version: 9
Interval Since Last Report: 455519 sec
Crashes Since Last Report: 17
Per-App Interval Since Last Report: 247306 sec
Per-App Crashes Since Last Report: 1
Anonymous UUID: 8A018342-778C-4D04-A696-CE20DB35A5A8
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000da086a34
VM Regions Near 0xda086a34:
CG backing stores 00000000c99ec000-00000000ca1c4000 [ 8032K] rw-/rw- SM=SHM
-->
Submap 00000000ffff0000-00000000ffff2000 r-x/r-x process-only submap
Application Specific Information:
objc[581]: garbage collection is OFF
Performing @selector(onSwellCommand
from sender REAPERSwell_button 0xb24d30
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 com.reFX.Nexus 0x0d218fa1 0xd206000 + 77729
1 com.reFX.Nexus 0x0d21e6b0 0xd206000 + 100016
2 com.reFX.Nexus 0x0d2abd81 VSTPluginMain + 465421
3 com.reFX.Nexus 0x0d21e467 0xd206000 + 99431
4 com.reFX.Nexus 0x0d2380be AUVSTViewEntry + 50542
5 com.reFX.Nexus 0x0d239b8c AUVSTViewEntry + 57404
6 com.reFX.Nexus 0x0d22b970 AUVSTEntry + 3426
7 com.reFX.Nexus 0x0d224bd8 0xd206000 + 125912
8 com.reFX.Nexus 0x0d2251fa 0xd206000 + 127482
9 com.reFX.Nexus 0x0d22bb77 AUVSTViewEntry + 39
10 com.apple.CoreServices.CarbonCore 0x9878e5f5 CallComponent + 223
11 com.apple.CoreServices.CarbonCore 0x9878e63e CallComponentDispatch + 29
12 com.apple.audio.toolbox.AudioToolbox 0x9a1eefb7 _AT_AudioUnitCarbonViewCreate + 73
13 com.cockos.reaper 0x0035bf71 AU_Plugin::ShowConfig(HWND__*, RECT*) + 1217
14 com.cockos.reaper 0x00227a2c _ZN5FxDsp10showConfigEP6HWND__P4RECTi. + 347
15 com.cockos.reaper 0x0024b0c9 _ZN7FxChain16displayDspConfigEP6HWND__i. + 312
16 com.cockos.reaper 0x00242d18 FxChain::dialogProc(HWND__*, unsigned int, unsigned long, long) + 20584
17 com.cockos.reaper 0x0023dc69 FxChain::staticDialogProc(HWND__*, unsigned int, unsigned long, long) + 73
18 com.cockos.reaper 0x0032b87e -[REAPERSwell_hwnd initChild:Parent:dlgProc:Param:] + 654
19 com.cockos.reaper 0x00331a7f -[REAPERSwell_modelesswindow initModeless:Parent:dlgProc:Param
utputHwnd:] + 559
20 com.cockos.reaper 0x0032f8ac SWELL_CreateDialog(SWELL_DialogResourceIndex*, char const*, HWND__*, long (*)(HWND__*, unsigned int, unsigned long, long), long) + 332
21 com.cockos.reaper 0x00248404 _ZN7FxChain10showDialogEbb. + 161
22 com.cockos.reaper 0x0015507c MediaTrack::ShowFxWindow(bool, bool, bool) + 124
23 com.cockos.reaper 0x00262fc6 addDialogProc(HWND__*, unsigned int, unsigned long, long) + 13270
24 com.cockos.reaper 0x00331e0a SwellDialogDefaultWindowProc(HWND__*, unsigned int, unsigned long, long) + 74
25 com.cockos.reaper 0x0032ad84 -[REAPERSwell_hwnd onSwellCommand:] + 356
26 com.apple.CoreFoundation 0x953c9091 -[NSObject performSelector:withObject:] + 65
27 com.apple.AppKit 0x9349acb3 -[NSApplication sendAction:to:from:] + 232
28 com.apple.AppKit 0x9349ab90 -[NSControl sendAction:to:] + 102
29 com.apple.AppKit 0x9349aa93 -[NSCell _sendActionFrom:] + 160
30 com.apple.AppKit 0x93499e50 -[NSCell trackMouse:inRect
fView:untilMouseUp:] + 2295
31 com.apple.AppKit 0x9351d351 -[NSButtonCell trackMouse:inRect
fView:untilMouseUp:] + 501
32 com.apple.AppKit 0x93498893 -[NSControl mouseDown:] + 943
33 com.apple.AppKit 0x934617b1 -[NSWindow sendEvent:] + 7533
34 com.apple.AppKit 0x933f96ff -[NSApplication sendEvent:] + 4788
35 com.cockos.reaper 0x001e36c9 -[REAPERapp sendEvent:] + 297
36 com.apple.AppKit 0x9338ac82 -[NSApplication run] + 1007
37 com.apple.AppKit 0x9361f18a NSApplicationMain + 1054
38 com.cockos.reaper 0x00002de9 _start + 208
39 com.cockos.reaper 0x00002d18 start + 40
Thread 1:: Dispatch queue: com.apple.libdispatch-manager
0 libsystem_kernel.dylib 0x98a6990a kevent + 10
1 libdispatch.dylib 0x993d4c58 _dispatch_mgr_invoke + 969
2 libdispatch.dylib 0x993d36a7 _dispatch_mgr_thread + 53
Thread 2:
0 libsystem_kernel.dylib 0x98a6902e __workq_kernreturn + 10
1 libsystem_c.dylib 0x95b08ccf _pthread_wqthread + 773
2 libsystem_c.dylib 0x95b0a6fe start_wqthread + 30
(Had to shorten this as Forum won't allow long posts 10000 characters long.