Crash at connecting to stored db connection

I get crashs while connecting/disconnecting to several stored db connections with the dropdown-field from the first toolbar-button and the second toolbar-button.

Sample:
- Connection 3 is active at startup
- Connect to Connection 1
- Disconnect from Connection 3
- Connect to Connection 2 -> crash

date/time : 2010-12-07, 15:38:08, 66ms
computer name : WSJH2
user name : jh <admin>
registered owner : Microsoft / Microsoft
operating system : Windows 7 x64 build 7600
system language : German
system up time : 6 hours 8 minutes
program up time : 11 seconds
processors : 2x Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz
physical memory : 2183/3738 MB (free/total)
free disk space : (C:) 220,23 GB
display mode : 1600x1200, 32 bit
process id : $544
allocated memory : 60,18 MB
executable : heidisql.exe
exec. date/time : 2010-12-07 13:35
version : 6.0.0.3626
compiled with : Delphi 2010
madExcept version : 3.0k
callstack crc : $d466ad4d, $1540c306, $1540c306
exception number : 1
exception class : EAccessViolation
exception message : Access violation at address 00761B18 in module 'heidisql.exe'. Read of address 00000000.

main thread ($7e8):
00761b18 heidisql.exe mysql_connection 2267 +1 TMySQLQuery.Col
006d5720 heidisql.exe Main 7886 +24 TMainForm.ListDatabasesGetText
00630350 heidisql.exe VirtualTrees TCustomVirtualStringTree.DoGetText
0062f6b4 heidisql.exe VirtualTrees TCustomVirtualStringTree.GetText
006302e3 heidisql.exe VirtualTrees TCustomVirtualStringTree.DoGetNodeWidth
0062afee heidisql.exe VirtualTrees TBaseVirtualTree.PaintTree
00622c44 heidisql.exe VirtualTrees TBaseVirtualTree.Paint
00544f4b heidisql.exe Controls TCustomControl.PaintWindow
0053f6c9 heidisql.exe Controls TWinControl.PaintHandler
0053fea8 heidisql.exe Controls TWinControl.WMPaint
00544ee5 heidisql.exe Controls TCustomControl.WMPaint
00619b3d heidisql.exe VirtualTrees TBaseVirtualTree.WMPaint
0040a8c9 heidisql.exe System 548 +0 @IntfCopy
0053ac48 heidisql.exe Controls TControl.WndProc
0053b56e heidisql.exe Controls TControl.WMMouseMove
0053ac48 heidisql.exe Controls TControl.WndProc
0053f510 heidisql.exe Controls TWinControl.WndProc
00625518 heidisql.exe VirtualTrees TBaseVirtualTree.WndProc
0053ebb0 heidisql.exe Controls TWinControl.MainWndProc
0049a5dc heidisql.exe Classes StdWndProc
77e700e3 ntdll.dll KiUserCallbackDispatcher
77e7010a ntdll.dll KiUserExceptionDispatcher
00630350 heidisql.exe VirtualTrees TCustomVirtualStringTree.DoGetText
0062f6b4 heidisql.exe VirtualTrees TCustomVirtualStringTree.GetText
006302e3 heidisql.exe VirtualTrees TCustomVirtualStringTree.DoGetNodeWidth
0062afee heidisql.exe VirtualTrees TBaseVirtualTree.PaintTree
00622c44 heidisql.exe VirtualTrees TBaseVirtualTree.Paint
00544f4b heidisql.exe Controls TCustomControl.PaintWindow
0053f6c9 heidisql.exe Controls TWinControl.PaintHandler
0053fea8 heidisql.exe Controls TWinControl.WMPaint
00544ee5 heidisql.exe Controls TCustomControl.WMPaint
00619b3d heidisql.exe VirtualTrees TBaseVirtualTree.WMPaint
0053ac48 heidisql.exe Controls TControl.WndProc
0053f510 heidisql.exe Controls TWinControl.WndProc
00625518 heidisql.exe VirtualTrees TBaseVirtualTree.WndProc
0053ebb0 heidisql.exe Controls TWinControl.MainWndProc
0049a5dc heidisql.exe Classes StdWndProc
77e700e3 ntdll.dll KiUserCallbackDispatcher
0054219d heidisql.exe Controls TWinControl.Repaint
0074b4be heidisql.exe helpers 2495 +6 InvalidateVT
006d1675 heidisql.exe Main 6611 +15 TMainForm.DBtreeInitChildren
0061d774 heidisql.exe VirtualTrees TBaseVirtualTree.DoInitChildren
00621638 heidisql.exe VirtualTrees TBaseVirtualTree.InitChildren
0062dbca heidisql.exe VirtualTrees TBaseVirtualTree.ToggleNode
00615710 heidisql.exe VirtualTrees TBaseVirtualTree.SetExpanded
006c38c8 heidisql.exe Main 2819 +49 TMainForm.InitConnection
006c35f4 heidisql.exe Main 2753 +30 TMainForm.SessionConnect
00526dbb heidisql.exe Menus TMenuItem.Click
00528377 heidisql.exe Menus TMenu.DispatchCommand
00529556 heidisql.exe Menus TPopupList.WndProc
0053ebb0 heidisql.exe Controls TWinControl.MainWndProc
005294a5 heidisql.exe Menus TPopupList.MainWndProc
0049a5dc heidisql.exe Classes StdWndProc
76f07df5 USER32.dll DispatchMessageW
0056b311 heidisql.exe Forms TApplication.ProcessMessage
0056b356 heidisql.exe Forms TApplication.HandleMessage
0056b681 heidisql.exe Forms TApplication.Run
007a673a heidisql.exe heidisql 66 +15 initialization
77913675 kernel32.dll BaseThreadInitThunk