I have a grid in form.
Form contains grid redraw method invoked by F3 key:

this.MousePointer = 11
_screen.mousepointer = 11
this.cmdFormSwitch1.setfocus()
this.gridbase1.columncount = 0
this.gridbase1.Init()
this.gridbase1.setfocus()
this.mousepointer = 0
_screen.mousepointer = 0

In VFP 5 this works OK.
In VFP 7, if I press F3 key some number of times, an error occurs:

Fatal error: Exception code=C0000005 @ 16.08.2001 15:55:01. Error log file: C:\PROGRAM FILES\MICROSOFT VISUAL FOXPRO 7\VFP7err.log
Called from - alguss line 115 {i:\raamat\ya\alguss.prg i:\raamat\ya\alguss.fxp}

Error points to line containing READ EVENTS command.
How to avoid this error ?