wine users - May 2009 - Query about Forte Agent 2 in Wine 1.0.1

I use Forte Agent 2 as a usenet news reader. I normally initialise the program
through a button which I have set up on a Panel. (kde 3, PCLinuxOS).
The argument set for this button is
WINEPREFIX="/home/stuart/Programs/Agent" wine
/home/stuart/Programs/Agent/Agent.exe
"z:\home\stuart\Programs\agent\Data\AGENT.INI"

Until recently (probably the upgrade of Wine) I could open a url from a 
message with a right click and Launch URL. This has now stopped working.
Following a suggestion I received earlier from the Forte Agent newsgroup I
changed the Options - General Preferences - URL and MIME settings - URL types to
use a batch file. The command is
start z:\home\stuart\bin\agent-showhttp %1
and the agent-showhttp file reads
#!/bin/sh
	firefox $* >/dev/null 2>&1 &

If I open the Agent program from the button on the panel, as above, if I try to
open a url with a right mouse click etc then nothing happens.
If, however, I cd to \home\stuart\Programs\agent\ in a console and use wine
agent.exe then
try to open the url via a mouse click then I get a message 
fixme:exec:SHELL_execute flags ignored: 0x00000500
in the console, but the url opens fine in Firefox.

Is this likely to be a problem associated with Wine, KDE, Agent or what ?
Any advice gratefully received.

wine actually comes with a tool that does that. Use :

winebrowser %1

fires the default configured browser and works fine here.

Thanks for the reply and the advice
I have done as you suggested and it seems to be working fine.