I am using SAM 440ep
Here are my observations
My OpenURL settings:
Name: IBrowse
Datas:Utilities_OS4.1.1/IBrowse/IBrowse  "%u"
Arexx port: IBROWSE
Arexx commands
Show  SHOW
Tofront: SCREENTOFRONT
Open URL: GOTOURL "%u"
New Window: NEWWINDOW "%u"
Tests for the IBrowse arexx commands from shell
Browser Open xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
9.Amiga OS 4:C> RX 'ADDRESS IBROWSE SHOW' 				OK
9.Amiga OS 4:C>  RX 'ADDRESS IBROWSE SCREENTOFRONT'	OK
9.Amiga OS 4:C> RX 'ADDRESS IBROWSE NEWWINDOW "
http://www.amigans.net/"'   OK
9.Amiga OS 4:C> RX 'ADDRESS IBROWSE GOTOURL "
http://www.amigans.net/"' OK
Tests of OpenURL from shell
9.Amiga OS 4:C> OpenURL 
http://www.amigans.net/
Could not launch browser
9.Amiga OS 4:C> OpenURL "
http://www.amigans.net/"Could not launch browser
9.Amiga OS 4:C> OpenURL 'http://www.amigans.net/'
Could not launch browser
9.Amiga OS 4:C> OpenURL URL 
http://www.amigans.net/Could not launch browser
Browser closed  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
5.Amiga OS 4:C> OpenURL URL 
http://www.amigans.net/Could not launch browser
Snoopy output here
Log Generated by; Snoopy 53.28 (7.7.2012)
00001 : Shell Process   : o.k. = GetVar("_pchar",0x591ECD18,32,0x00000200) [15uS]
00002 : Shell Process   : o.k. = GetVar("_mchar",0x591ECD18,32,0x00000200) [3uS]
00003 : Shell Process   : o.k. = GetVar("_pchar",0x591ECD18,32,0x00000200) [5uS]
00004 : Shell Process   : o.k. = GetVar("_mchar",0x591ECD18,32,0x00000200) [3uS]
00005 : Shell Process   : FAIL = FindSegment("OpenURL",0x00000000,USER) [14uS]
00006 : Shell Process   : FAIL = FindSegment("OpenURL",0x00000000,SYSTEM) [5uS]
00007 : Shell Process   :        CurrentDir("<untracked>")
00008 : Shell Process   : o.k. = Lock("OpenURL",SHARED) [166uS]
00009 : Shell Process   : o.k. = ExamineObject(0x591ECC88) [57uS]
00010 : ENV/env-handler 52.2  : FAIL = Lock("ENVARC:ELF.LazyBinding",SHARED) [86uS]
00011 : Shell Process   : o.k. = LoadSeg("OpenURL") = [0x165E876D] [2816uS]
00012 : Shell Process   : o.k. = Lock("OpenURL",SHARED) [126uS]
00013 : Shell Process   : DIR  = ParentDir("OpenURL") [26uS]
00014 : Shell Process   :        CurrentDir("<untracked>")
00015 : OpenURL         : o.k. = Open("CONSOLE:",OLD) = [0x15DA516C] [207uS]
00016 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00017 : OpenURL         : 0    = FindSegmentStackSize("OpenURL") [66uS]
00018 : OpenURL         : -----> RunCommand(0x165E876D "OpenURL",,"URL 
http://www.amigans.net/",28) 
00019 : OpenURL         : 0    = FindSegmentStackSize("OpenURL") [3uS]
00020 : OpenURL         : o.k. = [exec] OpenLibrary("newlib.library",52) [17uS]
00021 : OpenURL         : o.k. = IsInteractive("<untracked>")
00022 : OpenURL         : o.k. = IsInteractive("<untracked>")
00023 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00024 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00025 : OpenURL         : FAIL = GetVar("EXEC_IMPORT_LOCAL",0x57CE9D18,8,0x00000200) [21uS]
00026 : OpenURL         : o.k. = Lock("Amiga OS 4:C",SHARED) [85uS]
00027 : OpenURL         :        CurrentDir("Amiga OS 4:C")
00028 : OpenURL         : o.k. = [exec] OpenLibrary("intuition.library",37) [19uS]
00029 : OpenURL         : o.k. = [exec] OpenLibrary("icon.library",37) [19uS]
00030 : OpenURL         : o.k. = [exec] OpenLibrary("utility.library",37) [4uS]
00031 : OpenURL         : o.k. = [exec] OpenLibrary("openurl.library",4) [65uS]
00032 : OpenURL         :        CurrentDir("<untracked>")
00033 : OpenURL         : <----- RunCommand(0x165E876D "OpenURL",,"URL 
http://www.amigans.net/",28) = 10 [0x0000000A] [29874
00034 : Shell Process   : o.k. = SetMode("<untracked>",[LINE]) [828uS]
00035 : Shell Process   : FAIL = GetVar("_Title",0x593CF60C,256,0x00000200) [22uS]
00036 : Shell Process   : FAIL = GetVar("Echo",0x591ECD38,32,0x00000200) [11uS]
00037 : Shell Process   : FAIL = GetVar("OldRedirect",0x591ECD38,32,0x00000200) [5uS]
00038 : Shell Process   : FAIL = GetVar("KeepDoubleQuotes",0x591ECD38,32,0x00000200) [5uS]
00039 : Shell Process   : FAIL = GetVar("Interactive",0x591ECD38,32,0x00000200) [5uS]
=========
5.Amiga OS 4:C> OpenURL 
http://www.amigans.net/Could not launch browser
Log Generated by; Snoopy 53.28 (7.7.2012)
00001 : Shell Process   : o.k. = GetVar("_pchar",0x591ECD18,32,0x00000200) [16uS]
00002 : Shell Process   : o.k. = GetVar("_mchar",0x591ECD18,32,0x00000200) [4uS]
00003 : Shell Process   : o.k. = GetVar("_pchar",0x591ECD18,32,0x00000200) [4uS]
00004 : Shell Process   : o.k. = GetVar("_mchar",0x591ECD18,32,0x00000200) [3uS]
00005 : Shell Process   : FAIL = FindSegment("OpenURL",0x00000000,USER) [13uS]
00006 : Shell Process   : FAIL = FindSegment("OpenURL",0x00000000,SYSTEM) [4uS]
00007 : Shell Process   :        CurrentDir("<untracked>")
00008 : Shell Process   : o.k. = Lock("OpenURL",SHARED) [245uS]
00009 : Shell Process   : o.k. = ExamineObject(0x591ECC88) [62uS]
00010 : ENV/env-handler 52.2  : FAIL = Lock("ENVARC:ELF.LazyBinding",SHARED) [86uS]
00011 : Shell Process   : o.k. = LoadSeg("OpenURL") = [0x165E876D] [2932uS]
00012 : Shell Process   : o.k. = Lock("OpenURL",SHARED) [126uS]
00013 : Shell Process   : DIR  = ParentDir("OpenURL") [26uS]
00014 : Shell Process   :        CurrentDir("<untracked>")
00015 : OpenURL         : o.k. = Open("CONSOLE:",OLD) = [0x15DA518C] [203uS]
00016 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00017 : OpenURL         : 0    = FindSegmentStackSize("OpenURL") [67uS]
00018 : OpenURL         : -----> RunCommand(0x165E876D "OpenURL",,"
http://www.amigans.net/",24) 
00019 : OpenURL         : 0    = FindSegmentStackSize("OpenURL") [3uS]
00020 : OpenURL         : o.k. = [exec] OpenLibrary("newlib.library",52) [16uS]
00021 : OpenURL         : o.k. = IsInteractive("<untracked>")
00022 : OpenURL         : o.k. = IsInteractive("<untracked>")
00023 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00024 : OpenURL         : o.k. = IsInteractive("CONSOLE:")
00025 : OpenURL         : FAIL = GetVar("EXEC_IMPORT_LOCAL",0x57A74D18,8,0x00000200) [22uS]
00026 : OpenURL         : o.k. = Lock("Amiga OS 4:C",SHARED) [91uS]
00027 : OpenURL         :        CurrentDir("Amiga OS 4:C")
00028 : OpenURL         : o.k. = [exec] OpenLibrary("intuition.library",37) [19uS]
00029 : OpenURL         : o.k. = [exec] OpenLibrary("icon.library",37) [18uS]
00030 : OpenURL         : o.k. = [exec] OpenLibrary("utility.library",37) [5uS]
00031 : OpenURL         : o.k. = [exec] OpenLibrary("openurl.library",4) [64uS]
00032 : OpenURL         :        CurrentDir("<untracked>")
00033 : OpenURL         : <----- RunCommand(0x165E876D "OpenURL",,"
http://www.amigans.net/",24) = 10 [0x0000000A] [31283uS]
00034 : Shell Process   : o.k. = SetMode("<untracked>",[LINE]) [815uS]
00035 : Shell Process   : FAIL = GetVar("_Title",0x593CF60C,256,0x00000200) [23uS]
00036 : Shell Process   : FAIL = GetVar("Echo",0x591ECD38,32,0x00000200) [10uS]
00037 : Shell Process   : FAIL = GetVar("OldRedirect",0x591ECD38,32,0x00000200) [5uS]
00038 : Shell Process   : FAIL = GetVar("KeepDoubleQuotes",0x591ECD38,32,0x00000200) [5uS]
00039 : Shell Process   : FAIL = GetVar("Interactive",0x591ECD38,32,0x00000200) [5uS]
Tests with two migaguide documents
Using the AG document below i do get the error: OpenURL : file not executable.
(as wel as IBrowse is open or not)
I just copied those openurl links from the latest AmiCygnix guide, where i got the error 'Could not launch browser"
(
====================
@database "testopenURL"
@node main "Test OpenURL"
 @{"Lightweight X11 Desktop Environment" system "OpenURL URL 
http://lxde.org/lxde "}
  @{" 
http://openbox.org/wiki/Main_Page " system "OpenURL URL 
http://openbox.org/wiki/Main_Page "}
  Amiga Bourne Compatible Shell. Here you can donate him for his great work:
     @{" 
http://amigaos.dk " system "OpenURL URL 
http://amigaos.dk"}
@endnode
==============