You might have tried this already, but I guess there is no harm in doing this if you didn't. Back up your SRO subfolder(save it somewhere else, preferably zipped or winrar'ed). Uninstall SRO, and clean your PC (virus, useless cached stuff, useless software). Try using Norton or regcleaner or something. Then read the online documentation that Joymax has regarding errors in installation. Download the installation from the yahoo link they have provided. the do another installation.
Some friends had this problem, but after doing the abovementioned, their installation worked.
If it still does not, ... err... try mentioning it at the SRO forum inside
http://www.silkroadonline.net?