winforms - VB.NET OpenFileDialog Latency on Win7 -

winforms - VB.NET OpenFileDialog Latency on Win7 -

i have winform, vbexpress 2008 single button , code behind illustrate problem:

private sub button1_click(byval sender system.object, byval e system.eventargs) handles button1.click openfiledialog1.showdialog() msgbox(openfiledialog1.filename) end sub

when select file (in case little pdf's) getting 3 6 sec delay after selecting file until goes on next statement, in case msgbox.

if repeat selecting same file sec time, don't delay. but, if exit programme , re-start it, delay 1 time again (one time). after first 1 hangs looks hangs ever 7 9 tries , window says "not responding" few seconds. don't have problem on vista or xp.

if select same file on , over, might hang 1st, 2nd , 12th time. close programme seek same again, might 1st, 3rd , 9th time. never same - if running out of resources , clearing cache.

i've watched task manager during delay , don't see unusual coming up. have new computer operating properly. thought maybe norton net security -- turned off , made no difference.

can give me clue might going on and/or how might trace source of delay bottom of it? i've tried know isolate problem , running out of ideas. don't see other posts particular thing.

project + properties, debug tab, tick "enable unmanaged code debugging". run programme , select output window in vs. open dialog. see in output window crapload of unmanaged dlls getting loaded process.

these shell extension handlers installed on machine. bad ones can impact programme in unpleasant ways, much describe in question. utilize sysinternals' autoruns utility command on this. start disabling ones not made microsoft.

vb.net winforms visual-studio-2008