Try removing your preferences file and trying to start it up again (search for preferences.txt in your user folder, but not the one inside 'lib' in the Processing install). If that works, please file a bug and post both copies of the preferences.txt along with it.

Thanks ben very much, but it doesn't work yet. I post here both copies of the preferences.txt as follows.

the origional preferences.txt:

-------------------------------------------------------------------------------------------

export.application.fullscreen=false
preproc.imports.list=java.applet.*,java.awt.Dimension,java.awt.Frame,java.awt.event.MouseEvent,java.awt.event.KeyEvent,java.awt.event.FocusEvent,java.awt.Image,java.io.*,java.net.*,java.text.*,java.util.*,java.util.zip.*,java.util.regex.*
editor.font.macosx=Monaco,plain,10
preproc.web_colors=true
last.sketch2.path=I:\++I.D.++\Processing\++Exercise+Samples++\Einstein_DotMatrix_String\Einstein_DotMatrix_String.pde
export.application.platform=true
update.check=true
default.window.width=500
update.id=8239089144583276322
editor.indent=true
editor.font=Monospaced,plain,12
editor.window.height.default=600
run.options.memory=true
preproc.imports=java.applet,java.awt,java.awt.image,java.awt.event,java.io,java.net,java.text,java.util,java.util.zip,java.util.regex
editor.divider.size=2
default.window.height=600
editor.caret.blink=true
preproc.color_datatype=true
export.applet.separate_jar_files=false
preproc.output_parse_tree=false
run.window.bgcolor=#F0F0F0
console.lines=4
console.error.file=stderr.txt
run.options.memory.maximum=512
editor.tabs.expand=true
editor.window.height.min=530
editor.keys.home_and_end_travel_far=false
console=true
run.present.exclusive.macosx=true
editor.tabs.size=2
console.length=500
last.sketch0.location=441,50,670,890,706
last.sketch2.location=781,304,500,618,434
run.options=
console.auto_clear=true
update.last=1277545480433
editor.window.width.min=400
run.present.exclusive=false
export.application.platform.linux=false
editor.keys.home_and_end_travel_far.macosx=true
editor.window.height.min.windows=530
run.present.bgcolor=#666666
export.application.platform.windows=true
run.options.memory.initial=64
editor.keys.alternative_cut_copy_paste=true
editor.window.width.default=500
console.output.file=stdout.txt
preproc.substitute_unicode=true
run.present.stop.color=#cccccc
editor.external=false
last.screen.height=1050
editor.keys.shift_backspace_is_delete=true
editor.window.height.min.macosx=450
last.sketch.count=0
export.delete_target_folder=true
last.sketch0.path=I:\++I.D.++\Processing\++Exercise+Samples++\Scattered_Letters3_cn\Scattered_Letters3_cn.pde
preproc.substitute_floats=true
editor.keys.alternative_cut_copy_paste.macosx=false
browser.linux=mozilla
editor.invalid=false
sketchbook.path=I:\++I.D.++\Processing\++Exercise+Samples++
export.application.stop=true
editor.divider.size.windows=2
last.sketch1.path=I:\++I.D.++\Processing\++Exercise+Samples++\year_counter\year_counter.pde
preproc.enhanced_casting=true
run.display=1
last.sketch1.location=646,124,670,890,706
platform.auto_file_type_associations=true
editor.antialias=false
preproc.save_build_files=false
last.screen.width=1400
export.application.platform.macosx=false
-------------------------------------------------------------------------------------------

the new preferences.txt:

-------------------------------------------------------------------------------------------

export.application.platform.windows=true
preproc.save_build_files=false
preproc.substitute_floats=true
run.options=
editor.window.width.min=400
run.display=1
editor.divider.size=2
preproc.enhanced_casting=true
editor.divider.size.windows=2
editor.font=Monospaced,plain,12
editor.untitled.suffix=MMMdd
console.auto_clear=true
console.output.file=stdout.txt
editor.keys.home_and_end_travel_far.macosx=true
last.sketch.count=0
editor.window.height.min=530
export.application.platform=true
editor.keys.alternative_cut_copy_paste.macosx=false
export.application.stop=true
editor.window.height.min.macosx=450
preproc.output_parse_tree=false
editor.external=false
editor.indent=true
run.present.bgcolor=#666666
preproc.web_colors=true
editor.tabs.expand=true
run.present.stop.color=#cccccc
preproc.color_datatype=true
editor.keys.shift_backspace_is_delete=true
editor.window.height.min.windows=530
export.application.platform.linux=true
export.application.platform.macosx=true
export.applet.separate_jar_files=false
editor.antialias=false
editor.tabs.size=2
console.error.file=stderr.txt
preproc.substitute_unicode=true
console=true
run.present.exclusive.macosx=true
console.lines=4
run.options.memory.maximum=256
browser.linux=mozilla
update.check=true
run.window.bgcolor=#F0F0F0
editor.keys.home_and_end_travel_far=false
editor.keys.alternative_cut_copy_paste=true
export.delete_target_folder=true
platform.auto_file_type_associations=true
editor.caret.blink=true
editor.window.width.default=500
run.options.memory.initial=64
preproc.imports.list=java.applet.*,java.awt.Dimension,java.awt.Frame,java.awt.event.MouseEvent,java.awt.event.KeyEvent,java.awt.event.FocusEvent,java.awt.Image,java.io.*,java.net.*,java.text.*,java.util.*,java.util.zip.*,java.util.regex.*
run.options.memory=false
export.application.fullscreen=false
editor.invalid=false
last.sketch.restore=true
editor.font.macosx=Monaco,plain,10
editor.window.height.default=600
console.length=500
run.present.exclusive=false
editor.untitled.prefix=sketch_
-------------------------------------------------------------------------------------------

thanks again for your concern.

Are you using a 64-bit version of Windows 7?

Have you downloaded the “expert” version of Processing, or the version that includes Java?

So 185 works fine, but 186 doesn't?  Could you clarify at what point it stopped working for your system?  This might be better placed as a bug report on Google Code.

the system is 32-bit windows 7. And what I have downloaded is the version that includes Java but not the expert version, which is much smaller than what I've downloaded in file size.

hi jeff_g, I'm afraid I couldn't catch your meaning of "clarify at what point it stopped working ", it just can't start to run, with the prompt window titled "Launch4j" and tell me An error occurred while starting the application.