hey ... dont know if your still having trouble, but i had this exact problem and figured it out after 2 days ... Its what the guy said above, but il explain why ...
If you have an antivirus program running when you try to run ECSRO client it will (dependant upon your settings) treat ''sro_client.exe'' as a trojan and remove it =/ (gay) ... just a forwarning it IS NOT A TROJAN ... all you have to do is add your ECSRO folder (C:/Programfiles/ECSRO) to your resident shield's exception list. OTHERWISE your virus program will DELETE ''sro_client.exe'' which is essential to running without ??????????????????? (the question mark error)
What i am refering to above is for AVG users (with regards to resident shield) but basicly if you just turn off your anti-virus software when playing it should work ... from experience your xp firewall will give you the same ??????? error the first time you launch ECSRO with your antivirus software off, but then it will give you the option to ''ALLOW'' it (this will pop up automatically after the client closes unexpectedly) so just CLICK the ALLOW button for firewall, and HEY PESTO XD next time you go to login it should work ... well thats my 2 days worth of trying to figure out the same problem and it worked fine for me ... hope this helps m8 ;) let me know how you get on :handsdown:
BUT don't EVER use the ECSRO launcher UNLESS your antivirus is switched OFF or you have added C:/programfiles/ECSRO to your Antivirus' ''exceptions'' list... otherwise the file ''sro_client.exe WILL get deleted and you will have to re-install =/ (bummer) =p