error in VRTool : access violation

Hello,
I have often some errors :
"Access violation at address 00622529 in module 'VRTool.exe'. Read of address 0000000."
One case I get this is each time I uncheck one trace to hide it from main window.
Any idea why ?
I have often some errors :
"Access violation at address 00622529 in module 'VRTool.exe'. Read of address 0000000."
One case I get this is each time I uncheck one trace to hide it from main window.
Any idea why ?